Metastability and polarization effects in a pn heterojunction device due to deep states.

Unusual metastable and polarization behavior has been observed for al(0.48)ln(0.52)As/Ga(0.47)ln(0.53)As avalanche photodiodes by capacitance spectroscopy. The metastability arises from interplay of the isotype heterojunction barrier with defects in the Al(0.48)ln(0.52)As layer. Defect occupation controls the reverse bias characteristics of the device while the heterojunction presents a barrier to carrier capture by the defects.