In situ grown single crystal aluminum as a nonalloyed ohmic contact to n-ZnSe by molecular beam epitaxy

Abstract

Novel ohmic contacts to n-ZnSe are demonstrated using single crystal Al films deposited on epitaxially grown ZnSe (100) by molecular beam epitaxy. Electron backscatter diffraction confirmed the single crystalline structure of the Al films. The (110)-oriented Al layer was rotated 45° relative to the substrate to match the ZnSe (100) lattice constant. The as-grown Al-ZnSe contact exhibited nearly ideal ohmic electrical characteristics over a large doping range of n-ZnSe without any additional treatment. The contact resistances are in a range of 10−3Ωcm2 for even lightly doped ZnSe (∼1017cm−3). Leaky Schottky behavior in lightly doped ZnSe samples suggested that Al-ZnSe formed a low-barrier height, Schottky limit contact. In situ grown Al could act as a simple metal contact to n-ZnSe regardless of carrier concentration with lower resistance compared to other reported contacts in literary studies. The reported novel metallization method could greatly simplify the ZnSe-based device fabrication complexity and lower the cost.