Ra. Roush et al., INFRARED PHOTOCONDUCTIVITY VIA DEEP COPPER ACCEPTORS IN SILICON-DOPED, COPPER-COMPENSATED GALLIUM-ARSENIDE PHOTOCONDUCTIVE SWITCHES, I.E.E.E. transactions on electron devices, 40(6), 1993, pp. 1081-1086
Silicon-doped, copper-compensated, semi-insulating gallium arsenide of
various doping parameters has been studied with respect to infrared p
hotoconductivity. This material is used as a photoconductive switch kn
own as the Bistable Optically controlled Semiconductor Switch (BOSS).
This device is a candidate for use in high-power, frequency agile puls
ed power applications. One limitation has been the relatively low cond
uctivity of the device during the ''on-state.'' Typically, silicon-dop
ed gallium arsenide is converted to semi-insulating gallium arsenide b
y the thermal diffusion of copper into the GaAs:Si. We have shown that
variation of the diffusion parameters can improve the on-state conduc
tivity by the enhancement of the concentration of a copper center know
n as CUB. The conductivity of the device 150 ns after irradiation from
a 20-ns FWHM laser pulse (lambda = 1.1 mum) is recorded for various i
ncident energies. This on-state conductivity saturates at a value that
is predicted by the densities of the copper levels and the mobility.
Also, the samples were irradiated with a 140-ps FWHM laser pulse (lamb
da = 2 mum) in order to excite holes from the copper levels into the v
alence band which demonstrates the nature of the hole recapture into t
he various copper acceptors.