Etching of GaSb with trisdimethylaminoantimony and triisopropylantimony in a metalorganic molecular beam epitaxy chamber

Abstract

Abstract Metalorganic molecular beam etching of GaSb using trisdimethylaminoantimony (TDMASb) and triisopropylantimony (TIPSb) is studied. When non-precracked TDMASb or TIPSb alone is supplied, reflection high-energy electron diffraction (RHEED) intensity oscillation is observed, indicating the monolayer-by-monolayer etching. Etching rate of GaSb by TDMASb is highest compared with those of GaAs, InP and GaP, corresponding to the weakest bond strength of GaSb. When the substrate temperature is decreased, the surface reconstruction is changed from (1 × 3) pattern to (1 × 5) due to the increase in the surface coverage of Sb. Activation energy for etching rate is simultaneously increased from 1.7 to 2.1 eV for TDMASb and from 1.1 to 1.8 eV for TIPSb, indicating that the etching process is affected by the surface coverage of Sb. Quadrupole mass spectroscopy measurement shows that isopropyl radicals are stable in high vacuum condition. It is considered that isopropyl-groups released from TIPSb molecules react with surface atoms and etch them. TIPSb is completely decomposed at around 380°C, while TDMASb at around 300°C, indicating that TDMASb easily releases much Sb atoms than TIPSb does. This leads to the larger activation energy for etching by TDMASb.