Reduction of the acceptor impurity background in GaAs grown by molecular beam epitaxy

Abstract
We report very high purity, unintentionally doped n‐type GaAs with the lowest acceptor background of all reported molecular beam epitaxy (MBE) GaAs layers. The residual acceptor concentration is 2.4×1013 cm3 and the residual donor concentration is 1.5×1014 cm3, yielding a compensation ratio of Na/Nd=0.160. The measured Hall mobility is 163 000 cm2/V s at 77 K with a peak value of 216 000 cm2/V s at 45.9 K. The limitations of the Hall mobility at 77 K as a figure of merit are discussed and more accurate figures of merit are considered. The initial preparation of the MBE system and the growth conditions leading to the reduced incorporation of acceptor impurities are also presented.

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