Growth of Al/sub x/Ga/sub 1-x/N by plasma assisted MOCVD

Abstract

Thin films Al/sub x/Ga/sub 1-x/N were grown on (0001) sapphire substrates by plasma assisted metal-organic chemical vapor deposition (PA-MOCVD). Plasma-cracked N/sub 2/, trimethylaluminum (TMAl) and trimethylgallium (TMGa) were used as nitrogen, aluminum and gallium sources, respectively. The results of energy dispersive X-ray (EDX) measurements performed at room temperature yielded the linear dependence of molar fraction of Al (x) on molar fraction of vapor phase of TMAl/(TMAl + TMGa). The dependence of the band gap energy on the molar fraction of Al (x) showed quadratic expression, E/sub g/ (x) = 3.35 + 1.55x + 1.3x/sup 2/ eV. Al/sub x/Ga/sub 1-x/N layers with x < 0.34 show n-type conduction with room temperature mobilities in the range of 5 to 10 cm/sup 2//V/spl middot/s, and electron concentrations of 9.0 /spl times/ 10/sup 16/ to 1.4 /spl times/ 10/sup 19/cm/sup -3/.