Abstract

In recent years, much attention has been focused on carrier emission rates and cross-well motion in semiconductor quantum well structures because the efficiency and response speed of many MQW optoelectronic devices depend on the dynamics of vertical carrier transport processes. Thermionic emission is believed to be the principal mechanism for the escape of the carriers from each individual quantum well. In most cases, measurements of the transport dynamics have been carried out in structures that contain multiple quantum wells. However in multiple well structures, effects such as resonant tunneling and carrier retrapping make it difficult to unambiguously separate the effects from one another. In recent measurements on single quantum wells with asymmetric barriers, we monitored electron and hole sweep-out rates simultaneously as a function of electric field⁽¹⁾, and showed that the carrier emission from the wells is thermionic in nature, but this preliminary analysis did not give very good quantitative agreement with the conventional thermionic emission model⁽²⁾. In this paper, we will present a study of the emission for both carrier types as a function of temperature and electric field in order to fully evaluate the applicability of the thermionic emission model to the process of carrier escape in a single quantum well.

© 1993 Optical Society of America