Improvement of two-dimensional electron gas concentration in selectively doped GaAs/N-AlGaAs heterostructures by atomic planar doping

Atomic planar doping of Si into an AlGaAs layer was successfully applied to molecular-beam-epitaxially grown selectively doped GaAs/N-AlGaAs heterostructures in an attempt to improve the two-dimensional electron gas concentration. The dependence of the electron gas characteristics on the atomic-planar-doping conditions such as sheet doping density, spacer thickness, and substrate temperature was investigated. A thirty percent improvement in electron gas concentration, up to a value of 1.2×1012 cm−2, was achieved with almost the same mobility of 3.5×104 cm2/V s as in a conventional structure. Correspondingly, the characteristics of high electron mobility transistors, fabricated on such planar-doped GaAs/N-AlGaAs heterostructures, were also improved.