Four types of lateral photoconductive semiconductor switches (PCSS) made of different materials are compared. The
PCSS made of GaAs, InP and Si are triggered by laser pulse to find out the effect on the voltage transmission efficiency.
The peak voltage transmission efficiency of GaAs PCSS is 93% at the biased voltage 1500V with the laser energy 1mJ.
On the same condition, the InP switch is only 63.63%. The Si switch can only acquire the efficiency 0.02%. The
difference of different materials employed for PCSS is analysed. The SiC PCSS is compared with the GaAs PCSS in the
relationship of the optical energy and the conduction resistance to analysed the voltage transmission efficiency in
theoretics. The university of Missouri-Columbia has done some research on the SiC PCSS, some of their experiment
results are reported.
High power sub-nanosecond electrical pulse system based on photoconductive semiconductor switch (PCSS) is reported.
To get high power sub-nanosecond electrical pulse, experiments of three kinds of switches such as a lateral
semi-insulating GaAs PCSS, gas gap added into the two electrodes of the switch on the GaAs chip and combinatorial
switchs of GaAs PCSS with gas switch are triggered by nano-second laser pulse. The source of the triggered laser is
YAG lasers, and the width of the laser is about 3.5 ns. A maximum current is only 38A by a single 3.5mm PCSS. The
combinatorial switch of a 3mm-gap PCSS and a 0.6~0.8mm gas switch is triggered at the biased voltage 4000V, a high
current pulse is acquired with the peak value above 5160A, and ns risetime. The voltage transmission efficiency is more
than 100% (129%), which can not be answered for the ohm-theorem. This phenomena is explained with the theorem of
The experiment result of series photoconductive switches triggered by ns laser pulse is reported. The series switches is composed by two semi-insulating GaAs photoconductive switches with 3mm electrode gap and the electrodes at two sides. Both electrodes touch each other. When it is triggered by ns laser pulse about 2mJ at 532nm, with the biased voltage of 1200V, linear mode of the series switches is observed. Then, laser energy and the biased voltage add to 5mJ and 4000V, the series switches still works in linear mode. When it is triggered by ns laser pulse about 6mJ at 1064nm, with the biased voltage of 3500V, the series switches works in linear mode. When laser energy and the biased voltage are 10mJ and 4000V, the series switches gives a double wave crest waveform. However, with the biased voltage of 6700V and laser energy of 15mJ, series switches gives trend of nonlinear mode. When laser energy rises to 20mJ, nonlinear mode is clearer. Even at 5000V and 30mJ, trend of nonlinear mode is observed. The results indicate that double wave crest appears while series switches works from linear mode to nonlinear mode. Capacitance effect caused by electrodes of switches touch is discussed. And explanation is given that double wave crest is attributed to surge caused by capacitance. When biased voltage and laser energy are enough, high gain of carries is very obvious. Effect of capacitance decreases and double wave crest disappears. Then the series switches is going to nonlinear mode. This explanation matches experiment result.
The experiment result of semi-insulating GaAs photoconductive semiconductor switch (PCSS) with different electrode
gaps triggered by semiconductor laser is reported. With the biased voltage of 500V, the semi-insulating GaAs PCSS with
2mm electrode gap is triggered by laser pulse with 5ns pulse width and repetition rate of 15 kHz, then two groups of
electrical pulse samples indicate that laser pulse is instable when laser energy is very low. With the biased voltage of
210V, the GaAs PCSS with 0.5mm electrode gap is triggered by the laser pulse in several dozens nanoseconds at 905nm
with a repetition rate of 2 kHz. A stable linear electrical pulse is observed. When the energy of the laser increases, the
amplitude and the width of the electrical pulse also increase. It indicates that a stable electrical pulse is obtained while
laser energy is high. With the biased voltage of 2400V, the GaAs PCSS with 1mm electrode gap is triggered by laser
pulse about 100nJ in 40ns at 904nm. The GaAs PCSS switches a electrical pulse with a voltage up to 1700V. Carriers
accumulation effect is discussed and the critical value of carriers accumulation effect is given. The relation of the biased
voltage, electrode gap and carriers accumulation effect is also discussed. The concentration of deep EL<sub>2</sub> traps in GaAs
has a certain effect on nonlinear mode of GaAs PCSS.