Displacement photocurrents and screening effects in novel piezoelectric InGaAs/GaAs multiple-quantum-well P-I-N diodes

Abstract

Room-temperature time-resolved photocurrent measurements have been performed on novel InGaAdGaAs multiple-quantum-wet1 (MQW) P-CN diodes on (1 1 l ) B GaAs substrates, having an average electric field of opposite sign to the built-in field. Direct evidence for dipole formation, displacement photocurrents and out-of-well screening by photocarriers is found. In these piezoelectric structures the sign of the internal field can be controlled by an external modulating voltage and the optically pumped charges stored at the extremes of the diode MQW active region can be exiracted by appropriate puised biasing. Tie generated dipoie moment and its time evolution have been determined by an optical pump and electrical probe technique the spatial separation of electrons and holes accounts for the observation of slow recombination processes. The piezoelectric constant is evaluated for In,Ga,-,As (x = 17% In) from the zero-average-field condition.

First- and second-order piezoelectricity in III-V semiconductors

“…These ideas have been considered in the case of a multiple quantum well in p-i-n structures in which the in-well field in the active region is calculated as a combined result of the built-in voltage, due to the different doping levels of the p and n regions. 84,85 However, these models have been used in only few cases and it is often not clear what electrostatic model was used to derive the field.…”