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IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 26, NO. 21, NOVEMBER 1, 2014
Large Current GaAs PCSS Triggered by a Laser Diode Wei Shi, Nana Hao, Zhanglong Fu, Mengxia Li, Cheng Ma, Huaimeng Gui, Luyi Wang, Huan Jiang, and Juncheng Cao
Abstract— We have fabricated a 2-mm gap semi-insulating GaAs photoconductive semiconductor switch (PCSS), and obtained a 1.45-kA large current under a bias voltage of 6 kV when the PCSS was triggered by a 4-µJ commercial laser diode. An RLC transient circuit model was employed to get the electrical properties of the PCSS in the transient discharge process. The reason for the switch exiting from nonlinear operating mode was that the electric field across the switch dropped below the lock-on field. This letter shows the attractive prospect of a low-cost compact high-power pulse source with the GaAs PCSS. Index Terms— Photoconductive semiconductor switch (PCSS), laser diode (LD), nonlinear mode. Fig. 1.
Schematic diagram of a lateral GaAs PCSS.
I. I NTRODUCTION
G
ALLIUM arsenide photoconductive semiconductor switch is regarded as a promising pulse-power device for the outstanding properties, such as simple structure, low optical trigger energy, low timing jitter, high breakdown voltage, and large current [1]–[4]. It has been widely used in high speed electronics, pulse forming, and the generation of terahertz radiation. However, the application of GaAs PCSS requires it to be solid-state, compact, and low-cost [5], [6]. It is necessary to utilize the compact light source such as a laser diode (LD) instead of the desktop laser for GaAs PCSS triggering. The GaAs PCSS will operate in the nonlinear mode. In this case, a photon excites more than one electron-hole pair caused by the avalanche multiplication process, only under the condition that the electric field across the switch is above a curtain value (3.2 − 4.2 kV/cm in GaAs) [7]–[9]. Therefore, the possibility that PCSS is Manuscript received March 13, 2014; revised July 23, 2014; accepted August 14, 2014. Date of publication August 21, 2014; date of current version October 6, 2014. This work was supported in part by the National Basic Research Program of China under Grant 2014CB339802, in part by the National Natural Science Foundation of China under Grant 51377133, in part by the Project of State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, in part by the China’s Ministry of Education Doctoral Program Funds under Grant 20116118110014, and in part by the Shaanxi International Cooperation Project under Grant 2012KW-04. W. Shi, N. Hao, M. Li, C. Ma, H. Gui, L. Wang, and H. Jiang are with the Department of Applied Physics, Xi’an University of Technology, Xi’an 710048, China (e-mail: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]). Z. Fu and J. Cao are with the Key Laboratory of Terahertz Solid-State Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China (e-mail: [email protected]; [email protected]). Color versions of one or more of the figures in this letter are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/LPT.2014.2349576
triggered by a low optical power LD and outputs a large current will achieve [10], [11]. In our previous works, we obtained 1.5 kA current utilizing a 16 mJ desktop laser as the trigger, when the GaAs PCSS was biased at 2 kV [12]. However, in this letter, the PCSS delivered a 1.45 kA current under a bias voltage of 6 kV, when illuminated by a 4 μJ commercial LD that had the advantage of compact, low cost, and batch manufacturing. And we obtained the electrical properties of the PCSS discharge process through an RLC transient circuit. It meant that an inexpensive compact PCSS package was promisingly used in high power pulse source, such as firing sets, high-power trigger generator etc. II. E XPERIMENTAL S ETUP The schematic diagram of the lateral GaAs PCSS used in our experiment is shown in Fig. 1. The material of the PCSS was semi-insulating (SI) GaAs with a resistivity of 5 × 107 ·cm in total darkness and a doping concentration of 1.5 × 107 cm−3 . Moreover, the electron mobility was larger than 5000 cm2 /(V·s) and the thickness of substrate was 0.6 mm. Au/Ge/Ni electrodes were deposited on the surface of the PCSS by electron beam evaporation technique. And ohmic contacts were then made by annealing heat treatment. The GaAs PCSS had the electrodes at the distance of 2 mm, and each electrode with a size of 5 mm × 3 mm and a fillet radius of 1.1 mm. A 900 nm Si3 N4 film was deposited on the surface of the substrate as the passivation layer. In addition, the GaAs PCSS was installed on an Al2 O3 ceramic board covered with copper on the backside, which facilitated thermal dissipation.
1041-1135 © 2014 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.
SHI et al.: LARGE CURRENT GaAs PCSS TRIGGERED BY A LASER DIODE
Fig. 2.
2159
Test circuit for a GaAs PCSS.
The test circuit is shown in Fig. 2. The commercial LD (SPL PL90-3 nanosecond pulse laser diode) was used to trigger the GaAs PCSS, which delivered a peak optical power up to 75 W. The output laser from the LD was with a pulse width of 26 ns, a rising time of 7 ns, a wavelength of 905 nm, and a pulse energy of 4 μJ. Furthermore, the LD system was very small, so the PCSS which was triggered with the LD can be made into a compact package. The ceramic capacitor was charged by the high-voltage DC source through a resistor of 4 M, which provided the GaAs PCSS discharge circuit with sufficient power. When the GaAs PCSS was triggered with the LD in the condition of high DC voltage biased, the capacitor was discharged through the switch to the 0.1 resistor. Then we made the power supply voltage dropped to zero rapidly. The operating current was measured by a current monitor (Pearson Model 7427) with a bandwidth of 70 MHz, and recorded by a digital storage oscilloscope (LeCroy WAVERUNNER 64Xi) with a bandwidth of 600 MHz. III. R ESULTS AND D ISCUSSION
Fig. 3. The oscillating current waveform for a GaAs PCSS which is triggered with an LD. The result shows that there are two peak currents, the first one is 1520 A and the second is 180 A in this shot.
If wt2 =
5π 2 ,
then I2 =
U0 −δ 5π e 2w wL
(3)
Equation (2) is divided by (3), we get: 2π L1 = eδ w L2
(4)
Finally, we have deduced that the inductance can be expressed as in L=
1 T2 · C 4π 2 + [In(I2 /I2 )]2
(5)
Where T is the time period of 3.8 × 10−6 s in the waveform, I1 and I2 are two peak currents of 1520 A and 180 A in adjacent time period respectively, C is the charging capacitor of 930 nF. So we can conclude that the inductance is about 350 nH in our experiment.
A. System Inductance Measurement In order to obtain the value of the system inductance in our experiment, we have tested an oscillating current waveform (See Fig. 3). Fig. 3 shows the oscillating current waveform of the GaAs PCSS. The bias voltage was 1.6 kV, the incident pulse energy from the LD was only 4 μJ, and the value of the charging capacitor was 930 nF. In an RLC transient circuit model, when it meets the condition of R < 2 CL , namely, it is an RLC under-damped oscillation circuit. The transient current can be expressed as in i (t) = Where δ = If wt1 =
R 2L , w π 2,
=
Uo −δt e si n(wt) wL
1 LC
−
then I1 =
(1)
R2 . 4L 2
U0 −δ π e 2w wL
(2)
B. PCSS Current Fig. 4 shows a current waveform of the GaAs PCSS. The bias voltage was 6 kV, the incident pulse energy from the LD was only 4 μJ, and the value of the charging capacitor was 140 nF. From the figure, we can see the switch delivered an electrical pulse with the peak current of 1.45 kA, the time duration of 250 ns without lock-on effect. C. PCSS Transient Characteristics In order to get the reason that the GaAs PCSS exited from the nonlinear mode and then turned off, we analyzed the discharge properties of the switch, which required us to understand the current and voltage transient characteristics for the PCSS. So we considered the influence of the 0.1 load and the system inductance on dynamic voltage across the PCSS, and the circuit construction in our experiment. According to the factors above, obviously this circuit was
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Fig. 4. The current waveform for a GaAs PCSS which is triggered with an LD. A high current of 1.45 kA is delivered to a 0.1 load in this shot. The insert is the waveform of the optical energy.
IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 26, NO. 21, NOVEMBER 1, 2014
field is higher than the nonlinear threshold electric filed ET (4 kV/cm) required for negative differential resistance [7]–[9], intensive avalanche impact ionization occurs, which makes carriers multiply. However, if the electric field across the switch is not enough to sustain the avalanche multiplication, the PCSS begins to turn on. Fig. 5 shows the bias voltage of the PCSS decreases rapidly to close to the nonlinear threshold electric filed as soon as the discharge process begins. In this process, with the reduction of the “ON” state field across the switch, carrier avalanche multiplication becomes slow, but carrier number still increases. The priority that the carrier generation is greater than recombination becomes weaker. In the macroscopic view, the resistance of the switch continuously diminishes as a convex function, which leads that the increase of circuit current also decreases as a convex function until the current reaches the peak value. Because the switch keeps discharging, the electric field across the switch achieves lock-on field. At this moment, carrier recombination velocity is equal to the production rate. After a few nanoseconds, the electric field across the switch drops below the photo-activated charge domain sustaining electric field (lock-on field) caused by circuit discharge and dynamic partial voltage. The PACDs extinguished in the bulk of the switch before arriving the anode [7], [8]. Meanwhile, the carrier recombination velocity is much larger than the production rate, namely, avalanche ionization cannot compensate the loss. The discharge process enters into recovery phase, and the PCSS begins to quench. The output current for the PCSS decreases and the switch exits from the nonlinear mode. IV. C ONCLUSION
Fig. 5. The voltage and current waveforms for a GaAs PCSS which is triggered with an LD. The left ordinate gives the calculated value of the voltage across the PCSS. The right ordinate gives the value of current flowing through the PCSS which is charged to 6 kV in this shot.
an RLC circuit. Hence its transient characteristics can be expressed as in i dt di + i · R(t) + = U0 L· (6) dt c Where, L was the system inductance (in this experiment, the measured value was about 350 nH, see Chapter A, Section III in detail), i was the transient current of the PCSS, R(t) was the total of the 0.1 load resistance and the time-varying resistance of the PCSS, C was the charging capacitor of 140 nF, U0 was the initial voltage of the capacitor. Referring to (6) and Fig. 4, we can obtain the voltage and current characteristic curves for the GaAs PCSS, as shown in Fig. 5. From Fig. 4, we can see the PCSS operates in nonlinear mode. When the LD illuminates PCSS, a number of photonactivated charges (PACs) are generated. The PAC begins to nucleate and photon-activated charge domain (PACD) forms in the PCSS through the rising edge of the current waveform. When the electric field in the domain satisfies the avalanche breakdown condition, namely, the biased electric
We have switched 1.45 kA at 6 kV DC bias voltage in a low cost, compact package with a 4 μJ commercial laser diode. The electrical properties of the PCSS discharge process was analyzed by an RLC transient circuit. It met the PACD theory that the switch exited from the nonlinear operating mode as the electric field across the switch reduced below photo-activated charge domain sustaining electric field. The experiment meant that an inexpensive compact PCSS (with an LD) component had a high value for application, especially in the high power pulse source. ACKNOWLEDGMENT The authors would like to thank all of their colleagues who have contributed to this letter. R EFERENCES [1] G. M. Loubriel et al., “Photoconductive semiconductor switches,” IEEE Trans. Plasma Sci., vol. 25, no. 2, pp. 124–130, Apr. 1997. [2] F. Zutavem et al., “Photoconductive semiconductor switch experiments for pulsed power applications,” IEEE Trans. Electron Devices, vol. 37, no. 12, pp. 2472–2477, Dec. 1990. [3] W. Shi et al., “30 kV and 3 kA semi-insulating GaAs photoconductive semiconductor switch,” Appl. Phys. Lett., vol. 92, no. 4, pp. 043511-1–043511-3, Feb. 2008. [4] W. Shi, L. Zhang, H. Gui, L. Hou, M. Xu, and G. Qu, “Accurate measurement of the jitter time of GaAs photoconductive semiconductor switches triggered by a one-to-two optical fiber,” Appl. Phys. Lett, vol. 102, no. 15, pp. 154106-1–154106-3, Apr. 2013.
SHI et al.: LARGE CURRENT GaAs PCSS TRIGGERED BY A LASER DIODE
[5] W. Jiang et al., “Compact solid-state switched pulsed power and its applications,” Proc. IEEE, vol. 2, no. 7, pp. 1180–1196, Jul. 2004. [6] W. C. Nunnally, “Critical component requirements for compact pulse power system architectures,” IEEE Trans. Plasma Sci., vol. 33, no. 4, pp. 1262–1267, Aug. 2005. [7] W. Shi and L. Tian, “Mechanism analysis of periodicity and weakening surge of GaAs photoconductive semiconductor switches,” Appl. Phys. Lett., vol. 89, no. 20, pp. 202103-1–202103-3, Nov. 2006. [8] L. Tian and W. Shi, “Analysis of operation mechanism of semi-insulating GaAs photoconductive semiconductor switches,” J. Appl. Phys., vol. 103, no. 12, pp. 124512-1–124512-7, Jun. 2008.
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[9] G. M. Loubriel, M. W. O’Malley, and F. J. Zutavern, “Toward pulsed power uses for photoconductive semiconductor switches: Closing switches,” in Proc. IEEE Proc. 6th Pulsed Power Conf., Arlington, VA, USA, Jun. 1987, pp. 145–148. [10] A. Rosen et al., “8.5 MW GaAs pulse biased switch optically controlled by 2-D laser diode arrays,” IEEE Photon. Technol. Lett., vol. 2, no. 7, pp. 525–526, Jul. 1990. [11] G. M. Loubriel et al., “Triggering GaAs lock-on switches with laser diode arrays,” IEEE Trans. Electron Devices, vol. 38, no. 4, pp. 692–695, Apr. 1991. [12] W. Shi and Z. Fu, “2-kV and 1.5-kA semi-insulating GaAs photoconductive semiconductor switch,” IEEE Electron Devices Lett., vol. 34, no. 1, pp. 93–95, Jan. 2013.
IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 26, NO. 21, NOVEMBER 1, 2014
Large Current GaAs PCSS Triggered by a Laser Diode Wei Shi, Nana Hao, Zhanglong Fu, Mengxia Li, Cheng Ma, Huaimeng Gui, Luyi Wang, Huan Jiang, and Juncheng Cao
Abstract— We have fabricated a 2-mm gap semi-insulating GaAs photoconductive semiconductor switch (PCSS), and obtained a 1.45-kA large current under a bias voltage of 6 kV when the PCSS was triggered by a 4-µJ commercial laser diode. An RLC transient circuit model was employed to get the electrical properties of the PCSS in the transient discharge process. The reason for the switch exiting from nonlinear operating mode was that the electric field across the switch dropped below the lock-on field. This letter shows the attractive prospect of a low-cost compact high-power pulse source with the GaAs PCSS. Index Terms— Photoconductive semiconductor switch (PCSS), laser diode (LD), nonlinear mode. Fig. 1.
Schematic diagram of a lateral GaAs PCSS.
I. I NTRODUCTION
G
ALLIUM arsenide photoconductive semiconductor switch is regarded as a promising pulse-power device for the outstanding properties, such as simple structure, low optical trigger energy, low timing jitter, high breakdown voltage, and large current [1]–[4]. It has been widely used in high speed electronics, pulse forming, and the generation of terahertz radiation. However, the application of GaAs PCSS requires it to be solid-state, compact, and low-cost [5], [6]. It is necessary to utilize the compact light source such as a laser diode (LD) instead of the desktop laser for GaAs PCSS triggering. The GaAs PCSS will operate in the nonlinear mode. In this case, a photon excites more than one electron-hole pair caused by the avalanche multiplication process, only under the condition that the electric field across the switch is above a curtain value (3.2 − 4.2 kV/cm in GaAs) [7]–[9]. Therefore, the possibility that PCSS is Manuscript received March 13, 2014; revised July 23, 2014; accepted August 14, 2014. Date of publication August 21, 2014; date of current version October 6, 2014. This work was supported in part by the National Basic Research Program of China under Grant 2014CB339802, in part by the National Natural Science Foundation of China under Grant 51377133, in part by the Project of State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, in part by the China’s Ministry of Education Doctoral Program Funds under Grant 20116118110014, and in part by the Shaanxi International Cooperation Project under Grant 2012KW-04. W. Shi, N. Hao, M. Li, C. Ma, H. Gui, L. Wang, and H. Jiang are with the Department of Applied Physics, Xi’an University of Technology, Xi’an 710048, China (e-mail: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]). Z. Fu and J. Cao are with the Key Laboratory of Terahertz Solid-State Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China (e-mail: [email protected]; [email protected]). Color versions of one or more of the figures in this letter are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/LPT.2014.2349576
triggered by a low optical power LD and outputs a large current will achieve [10], [11]. In our previous works, we obtained 1.5 kA current utilizing a 16 mJ desktop laser as the trigger, when the GaAs PCSS was biased at 2 kV [12]. However, in this letter, the PCSS delivered a 1.45 kA current under a bias voltage of 6 kV, when illuminated by a 4 μJ commercial LD that had the advantage of compact, low cost, and batch manufacturing. And we obtained the electrical properties of the PCSS discharge process through an RLC transient circuit. It meant that an inexpensive compact PCSS package was promisingly used in high power pulse source, such as firing sets, high-power trigger generator etc. II. E XPERIMENTAL S ETUP The schematic diagram of the lateral GaAs PCSS used in our experiment is shown in Fig. 1. The material of the PCSS was semi-insulating (SI) GaAs with a resistivity of 5 × 107 ·cm in total darkness and a doping concentration of 1.5 × 107 cm−3 . Moreover, the electron mobility was larger than 5000 cm2 /(V·s) and the thickness of substrate was 0.6 mm. Au/Ge/Ni electrodes were deposited on the surface of the PCSS by electron beam evaporation technique. And ohmic contacts were then made by annealing heat treatment. The GaAs PCSS had the electrodes at the distance of 2 mm, and each electrode with a size of 5 mm × 3 mm and a fillet radius of 1.1 mm. A 900 nm Si3 N4 film was deposited on the surface of the substrate as the passivation layer. In addition, the GaAs PCSS was installed on an Al2 O3 ceramic board covered with copper on the backside, which facilitated thermal dissipation.
1041-1135 © 2014 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.
SHI et al.: LARGE CURRENT GaAs PCSS TRIGGERED BY A LASER DIODE
Fig. 2.
2159
Test circuit for a GaAs PCSS.
The test circuit is shown in Fig. 2. The commercial LD (SPL PL90-3 nanosecond pulse laser diode) was used to trigger the GaAs PCSS, which delivered a peak optical power up to 75 W. The output laser from the LD was with a pulse width of 26 ns, a rising time of 7 ns, a wavelength of 905 nm, and a pulse energy of 4 μJ. Furthermore, the LD system was very small, so the PCSS which was triggered with the LD can be made into a compact package. The ceramic capacitor was charged by the high-voltage DC source through a resistor of 4 M, which provided the GaAs PCSS discharge circuit with sufficient power. When the GaAs PCSS was triggered with the LD in the condition of high DC voltage biased, the capacitor was discharged through the switch to the 0.1 resistor. Then we made the power supply voltage dropped to zero rapidly. The operating current was measured by a current monitor (Pearson Model 7427) with a bandwidth of 70 MHz, and recorded by a digital storage oscilloscope (LeCroy WAVERUNNER 64Xi) with a bandwidth of 600 MHz. III. R ESULTS AND D ISCUSSION
Fig. 3. The oscillating current waveform for a GaAs PCSS which is triggered with an LD. The result shows that there are two peak currents, the first one is 1520 A and the second is 180 A in this shot.
If wt2 =
5π 2 ,
then I2 =
U0 −δ 5π e 2w wL
(3)
Equation (2) is divided by (3), we get: 2π L1 = eδ w L2
(4)
Finally, we have deduced that the inductance can be expressed as in L=
1 T2 · C 4π 2 + [In(I2 /I2 )]2
(5)
Where T is the time period of 3.8 × 10−6 s in the waveform, I1 and I2 are two peak currents of 1520 A and 180 A in adjacent time period respectively, C is the charging capacitor of 930 nF. So we can conclude that the inductance is about 350 nH in our experiment.
A. System Inductance Measurement In order to obtain the value of the system inductance in our experiment, we have tested an oscillating current waveform (See Fig. 3). Fig. 3 shows the oscillating current waveform of the GaAs PCSS. The bias voltage was 1.6 kV, the incident pulse energy from the LD was only 4 μJ, and the value of the charging capacitor was 930 nF. In an RLC transient circuit model, when it meets the condition of R < 2 CL , namely, it is an RLC under-damped oscillation circuit. The transient current can be expressed as in i (t) = Where δ = If wt1 =
R 2L , w π 2,
=
Uo −δt e si n(wt) wL
1 LC
−
then I1 =
(1)
R2 . 4L 2
U0 −δ π e 2w wL
(2)
B. PCSS Current Fig. 4 shows a current waveform of the GaAs PCSS. The bias voltage was 6 kV, the incident pulse energy from the LD was only 4 μJ, and the value of the charging capacitor was 140 nF. From the figure, we can see the switch delivered an electrical pulse with the peak current of 1.45 kA, the time duration of 250 ns without lock-on effect. C. PCSS Transient Characteristics In order to get the reason that the GaAs PCSS exited from the nonlinear mode and then turned off, we analyzed the discharge properties of the switch, which required us to understand the current and voltage transient characteristics for the PCSS. So we considered the influence of the 0.1 load and the system inductance on dynamic voltage across the PCSS, and the circuit construction in our experiment. According to the factors above, obviously this circuit was
2160
Fig. 4. The current waveform for a GaAs PCSS which is triggered with an LD. A high current of 1.45 kA is delivered to a 0.1 load in this shot. The insert is the waveform of the optical energy.
IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 26, NO. 21, NOVEMBER 1, 2014
field is higher than the nonlinear threshold electric filed ET (4 kV/cm) required for negative differential resistance [7]–[9], intensive avalanche impact ionization occurs, which makes carriers multiply. However, if the electric field across the switch is not enough to sustain the avalanche multiplication, the PCSS begins to turn on. Fig. 5 shows the bias voltage of the PCSS decreases rapidly to close to the nonlinear threshold electric filed as soon as the discharge process begins. In this process, with the reduction of the “ON” state field across the switch, carrier avalanche multiplication becomes slow, but carrier number still increases. The priority that the carrier generation is greater than recombination becomes weaker. In the macroscopic view, the resistance of the switch continuously diminishes as a convex function, which leads that the increase of circuit current also decreases as a convex function until the current reaches the peak value. Because the switch keeps discharging, the electric field across the switch achieves lock-on field. At this moment, carrier recombination velocity is equal to the production rate. After a few nanoseconds, the electric field across the switch drops below the photo-activated charge domain sustaining electric field (lock-on field) caused by circuit discharge and dynamic partial voltage. The PACDs extinguished in the bulk of the switch before arriving the anode [7], [8]. Meanwhile, the carrier recombination velocity is much larger than the production rate, namely, avalanche ionization cannot compensate the loss. The discharge process enters into recovery phase, and the PCSS begins to quench. The output current for the PCSS decreases and the switch exits from the nonlinear mode. IV. C ONCLUSION
Fig. 5. The voltage and current waveforms for a GaAs PCSS which is triggered with an LD. The left ordinate gives the calculated value of the voltage across the PCSS. The right ordinate gives the value of current flowing through the PCSS which is charged to 6 kV in this shot.
an RLC circuit. Hence its transient characteristics can be expressed as in i dt di + i · R(t) + = U0 L· (6) dt c Where, L was the system inductance (in this experiment, the measured value was about 350 nH, see Chapter A, Section III in detail), i was the transient current of the PCSS, R(t) was the total of the 0.1 load resistance and the time-varying resistance of the PCSS, C was the charging capacitor of 140 nF, U0 was the initial voltage of the capacitor. Referring to (6) and Fig. 4, we can obtain the voltage and current characteristic curves for the GaAs PCSS, as shown in Fig. 5. From Fig. 4, we can see the PCSS operates in nonlinear mode. When the LD illuminates PCSS, a number of photonactivated charges (PACs) are generated. The PAC begins to nucleate and photon-activated charge domain (PACD) forms in the PCSS through the rising edge of the current waveform. When the electric field in the domain satisfies the avalanche breakdown condition, namely, the biased electric
We have switched 1.45 kA at 6 kV DC bias voltage in a low cost, compact package with a 4 μJ commercial laser diode. The electrical properties of the PCSS discharge process was analyzed by an RLC transient circuit. It met the PACD theory that the switch exited from the nonlinear operating mode as the electric field across the switch reduced below photo-activated charge domain sustaining electric field. The experiment meant that an inexpensive compact PCSS (with an LD) component had a high value for application, especially in the high power pulse source. ACKNOWLEDGMENT The authors would like to thank all of their colleagues who have contributed to this letter. R EFERENCES [1] G. M. Loubriel et al., “Photoconductive semiconductor switches,” IEEE Trans. Plasma Sci., vol. 25, no. 2, pp. 124–130, Apr. 1997. [2] F. Zutavem et al., “Photoconductive semiconductor switch experiments for pulsed power applications,” IEEE Trans. Electron Devices, vol. 37, no. 12, pp. 2472–2477, Dec. 1990. [3] W. Shi et al., “30 kV and 3 kA semi-insulating GaAs photoconductive semiconductor switch,” Appl. Phys. Lett., vol. 92, no. 4, pp. 043511-1–043511-3, Feb. 2008. [4] W. Shi, L. Zhang, H. Gui, L. Hou, M. Xu, and G. Qu, “Accurate measurement of the jitter time of GaAs photoconductive semiconductor switches triggered by a one-to-two optical fiber,” Appl. Phys. Lett, vol. 102, no. 15, pp. 154106-1–154106-3, Apr. 2013.
SHI et al.: LARGE CURRENT GaAs PCSS TRIGGERED BY A LASER DIODE
[5] W. Jiang et al., “Compact solid-state switched pulsed power and its applications,” Proc. IEEE, vol. 2, no. 7, pp. 1180–1196, Jul. 2004. [6] W. C. Nunnally, “Critical component requirements for compact pulse power system architectures,” IEEE Trans. Plasma Sci., vol. 33, no. 4, pp. 1262–1267, Aug. 2005. [7] W. Shi and L. Tian, “Mechanism analysis of periodicity and weakening surge of GaAs photoconductive semiconductor switches,” Appl. Phys. Lett., vol. 89, no. 20, pp. 202103-1–202103-3, Nov. 2006. [8] L. Tian and W. Shi, “Analysis of operation mechanism of semi-insulating GaAs photoconductive semiconductor switches,” J. Appl. Phys., vol. 103, no. 12, pp. 124512-1–124512-7, Jun. 2008.
2161
[9] G. M. Loubriel, M. W. O’Malley, and F. J. Zutavern, “Toward pulsed power uses for photoconductive semiconductor switches: Closing switches,” in Proc. IEEE Proc. 6th Pulsed Power Conf., Arlington, VA, USA, Jun. 1987, pp. 145–148. [10] A. Rosen et al., “8.5 MW GaAs pulse biased switch optically controlled by 2-D laser diode arrays,” IEEE Photon. Technol. Lett., vol. 2, no. 7, pp. 525–526, Jul. 1990. [11] G. M. Loubriel et al., “Triggering GaAs lock-on switches with laser diode arrays,” IEEE Trans. Electron Devices, vol. 38, no. 4, pp. 692–695, Apr. 1991. [12] W. Shi and Z. Fu, “2-kV and 1.5-kA semi-insulating GaAs photoconductive semiconductor switch,” IEEE Electron Devices Lett., vol. 34, no. 1, pp. 93–95, Jan. 2013.
