Electron accumulation at undoped AlSb-InAs quantum wells: Theory

The problem of the origin of electron accumulation at undoped AlSb-InAs quantum wells is examined. The magnitude and temperature dependence of the two-dimensional electron density in an InAs well on the binding energy and concentration of donorlike defects in AlSb is derived in closed form. The excellent agreement between the predicted and experimental temperature data makes it possible to extract the density, binding energy, and identity of the donorlike defects in AlSb. A microscopic explanation for the negative-persistent-photoconductivity effect exhibited by this quantum-well system is proposed.