Selectively doped GaAs/N–AlGaAs heterostructures grown by molecular beam epitaxy for high electron mobility transistor IC applications

Abstract

Extremely high electron mobilities of 2.4×10⁶ cm²/V s (4.2 K) and 2.05×10⁵ cm²/V s (77 K) with a sheet electron concentration of about 5.3×10¹¹ cm⁻² were achieved in a selectively doped GaAs/N–AlGaAs heterostructure with a GaAs–AlGaAs heterostructure buffer layer grown by MBE. A new 3‐in.‐substrate MBE system having a cell‐substrate distance of 25 cm was developed, and sufficiently high uniformity (±1% variation in the layer thickness, doping concentration, and AlAs mole fraction of Si‐doped AlGaAs over a 56‐mm‐diam area) as well as high quality of a GaAs/N–AlGaAs heterostructure (electron mobility of 1.96×10⁵ cm²/V s at 77 K) for high electron mobility transistor IC application was achieved with the new MBE system.