Vertical growth characterization of InAs nanowires grown by selective area growth on patterned InP(111)B substrate by a MOCVD method

摘要

InAs nanowires (NWs) were selectively grown on hole patterned InP (11 1)B substrate by Metal-Organic Chemical Vapor Deposition (MOCVD). This study reports the vertical growth behavior of InAs NWs transitioned at a certain height and its difference under various growth conditions. This certain height is referred as "critical height." This is a boundary where both vertical and lateral growth occur. Under this height, only vertical growth takes place. Vertical growth characteristics were reported through the determination of the critical height of NWs. The critical height was investigated for its three growth conditions; growth temperature, molar flow rates of In and As sources. Increase in growth temperature induced increase in critical height. Increase in growth temperature enhances the mobility of In adatom. This further increases diffusion length on the sidewall surface. However, increased AsH3 molar flow rate decreased the critical height. The surface reaction of In adatoms on the top (1 1 1)B surface of InAs NWs was reduced by the formation of As trimer. As a result, reduced relative vertical growth rate decreased the critical height of InAs NWs. The critical height of InAs NWs, however, was not changed by the variation of the Tri-Methyl Indium (TMIn) molar flow rate. This variation doesn't affect the mobility of In adatom on the sidewall surface or the surface reaction rate on the top (1 1 1)B surface of NWs. Hence, we concluded that variation of the mobility of In adatom on the sidewall surface and relative vertical growth rate affect the critical height of InAs NWs.