Formation and properties of porous GaAs

Porous structures on n-type GaAs (100) can be grown electrochemically in chloride-containing solutions. Crystallographic etching of the sample is a precursor stage of the attack. Polarization curves reveal the existence of a critical onset potential for pore formation (PFP). The PFP is strongly dependent on the doping level of the sample and the presence of surface defects. Good agreement between the PFP and the breakdown voltage of the space charge layer is found. Surface analytical investigations by EDX, AES and XPS show that the porous structure consists mainly of GaAs and that anion uptake in the structure can only be observed after attack has been initiated. Photoluminescence measurements reveal - under certain conditions - visible light emission from the porous structure.