Dependence of apparent barrier height on barrier thickness for perpendicular transport in AlAs/GaAs singlehyphen;barrier structures grown by molecular beam epitaxy

摘要

Currenthyphen;voltage characteristics of singlehyphen;barrier AlAs/GaAs heterostructures measured over a wide temperature range are used to elucidate the mechanisms governing electron transport through these barriers. Five barriers, ranging in thickness from 14.2 to 150 Aring;, are examined. The results clearly illustrate Ggr;hyphen;band, elastichyphen;tunnelinghyphen;dominated transport for the thinnest barrier (14.2 Aring;) devices and thermionic emission characteristics for the thickest barrier (150 Aring;) devices. However, devices with an intermediate barrier thickness exhibited tunnelinghyphen;like currents larger than calculated lowhyphen;temperature elastic tunneling currents. This effect is apparently due to inelastic tunneling from the GaAs Ggr; band through the AlAsXhyphen;point barrier.