InGaAs photoconductor failure observation

We have realised an In0.53Ga0.47As photoconductor on semi-insulating InP substrate. The quantum efficiency of this device is 600% at 1.6 V polarisation and its rise time is 113 ps as measured by a picosecond dye laser at 0.6 ¿m wavelength. We have found that such devices are subject to catastrophic and instantaneous degradation similar to the burn-out phenomenon observed in GaAs MESFETs. The failed devices are studied by X-ray imaging and scanning electron microscope. The conclusion is that the degradation is initiated at ohmic contacts. A temperature increase then occurs leading to massive damage in the channel. Furthermore, a surface metallic migration of gold is also found.