DETERMINATION OF THE EFFECTIVE-MASS OF GAN FROM INFRARED REFLECTIVITYAND HALL-EFFECT

Infrared reflectivity and Hall effect measurements were performed on h ighly conducting n-type GaN (n approximate to 6X10(19) cm(-3)) bulk cr ystals grown by the high-pressure high-temperature method, Values of e lectron-plasma frequency and free-electron concentration were determin ed for each sample of the set of seven crystals. It enabled us to calc ulate the perpendicular effective mass of electrons in the wurtzite st ructure of GaN as m=0.22+/-0.02 m(0). Effects of nonparabolicity and a difference between parallel and perpendicular components of the effe ctive mass are small and do not exceed the experimental error. (C) 199 6 American Institute of Physics.