Heavy doping with Sn of GaAs layers grown by molecular beam epitaxy for non-alloyed ohmic contacts

Abstract

High Sn-doping of molecular beam epitaxy (MBE) grown GaAs layers for non-alloyed ohmic contacts is presented. The highly doped layers were studied by van der Pauw-Hall measurements, Raman spectroscopy, low-temperature photoluminescence and scanning electron microscope. The highest free electron concentration of 8×1018 cm−3 and the lowest resistivity of 8× ×10−4 Ω cm were achieved. Doping limit of Sn in GaAs is discussed. Using the heavily Sn-doped GaAs layers and the in situ Sn deposition the non-alloyed ohmic contacts with specific contact resistance of 8×10−5 Ω cm2 and highly linearI–V characteristics were obtained.