Gallium nitride growth using diethyl gallium chloride as an alternative gallium source

Diethyl gallium chloride (DEGaCl) was employed as an alternative gallium pr ecursor in the epitaxial growth of GaN for producing a hydride vapor-phase epitaxy (HVPE)-like growth chemistry in a metal-organic vapor-phase epitaxy (MOVPE) system. The standard 'two-step' GaN growth process was carried out using this Cl-containing precursor and compared to the conventional growth using trimethyl gallium (TMGa) source under identical reactor conditions. The growth rate during DEGaCl-based growth decreases with increasing temper ature, indicating that the growth front may be close to local thermodynamic equilibrium. A direct comparison of materials properties associated with t hese precursors in various structural combinations of buffer and high-tempe rature GaN epilayers was performed. Improved material properties and a sign ificant difference in the surface morphology were observed in the case of D EGaCl-based high-temperature growth, as determined by X-ray diffraction, ca pacitance-voltage, atomic force microscopy and photoluminescence measuremen ts. We attributed the improved growth behavior to the 'nearer-to-equilibriu m' growth front that could result from the presence of HCl-related etching reactions. (C) 2000 Elsevier Science B.V. All rights reserved.