Growth of AlxGa1-xN by plasma assisted MOCVD

Thin films Al_xGa_1-xN were grown on (0001) sapphire substrates by plasma assisted metal-organic chemical vapor deposition (PA-MOCVD). Plasma-cracked N₂, 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_g (x) = 3.35 + 1.55x + 1.3x² eV. Al_xGa_1-xN layers with x < 0.34 show n-type conduction with room temperature mobilities in the range of 5 to 10 cm²/V·s, and electron concentrations of 9.0 × 10¹⁶ to 1.4 × 10¹⁹cm^-3.