Hall mobility and carrier concentration in free-standing high quality GaN templates grown by hydride vapor phase epitaxy

Measured and calculated (without any adjustable material parameter) electro n Hall mobility and carrier concentration in the range of 26.5-273 K are re ported for a high-mobility free-standing bulk GaN grown by hydride vapor ph ase epitaxy. The peak electron mobility of 7386 cm(2)/V s at 48 K and a val ue of 1425 cm(2)/V s at 273 K were measured. An iterative solution of the B oltzmann equation was applied to calculate the mobility using the materials parameters either measured on the sample under study or recent values that are just becoming available with only the acceptor concentration being var iable. Using only one donor and one conducting layer system, the donor and acceptor concentrations of 1.76 x 10(16) and 2.4 x 10(15) cm(-3), respectiv ely, satisfy simultaneously the charge neutrality and electron mobility at all temperatures within the framework of the iterative method and measureme nts. The donor activation energy was determined to be 25.2 meV and is consi stent with the value of about 30 meV for the hydrogenic ground state in a d ilute semiconductor. The high electron mobility, low background impurity co ncentration, low compensation ratio, and negligible dislocation scattering demonstrate the high quality of the material studied. (C) 2001 Elsevier Sci ence Ltd. All rights reserved.