Two post-breakdown metastable phases in semi-insulating GaAs

A room temperature electrically induced metastability in semi-insulating (SI)-GaAs has recently been reported in which the normally high resistivity state of SI-GaAs converts into a low resistance state when breakdown electric fields are applied to the metal/SI-GaAs/metal system. The present study finds that this post-breakdown metastable state can be classified into two metastable phases, namely a metastable high current phase and a metastable low current phase. This effect resembles the poorly understood ‘lock-on’ effect utilized in high power photoconductive semiconductor switches. It is argued that instead of a short pulse of light photo-ionizing the SI-GaAs and causing a carrier avalanche current that does not ‘switch off’ at low biases, the same avalanche current and effects are being brought about by the electrical breakdown of the sample.