Effect Of Heavy Ga Doping On Defect Structure Of Sno2 Layers

Crystal defects in Ga-doped SnO2 grown on SnO2 buffer layers on r-plane sapphire by plasma-assisted molecular beam epitaxy have been analysed by transmission electron microscopy (TEM). The (101)-oriented epitaxial SnO2 buffer layers contain a high number of crystallographic shear plane (CSP) defects (approximate to 10(11)cm(-2)) and threading dislocations (TDs, approximate to 10(10)cm(-2)). However, their density reduces with increasing layer thickness. Whereas a Ga atomic concentration of 3.2x10(16)cm(-3) does not lead to any change in the defect structure of the SnO2 layers, heavily doped SnO2 layers ([Ga]approximate to 6.1x10(20)cm(-3)) contain a continuous network of coherent Ga-rich precipitates appearing as platelets in crystallographically equivalent SnO2(100) and SnO2(010) planes. Electron conduction through this network might explain the reduced electrical resistivity compared to semi-insulating SnO2 with lower Ga concentration (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim