IN-SITU CLEANING OF SIO2-PATTERNED GAAS SURFACE WITH TRISDIMETHYLAMINOARSINE FOR SELECTIVE REGROWTH

Trisdimethylaminoarsine (TDMAAs) has been used to clean SiO2-patterned GaAs surfaces prior to selective regrowth. Under TDMAAs pressure, the native oxide was completely removed at 480 degrees C which is 110 deg rees C lower than the temperature of thermal oxide desorption. Compare d to oxide removal with arsine, the morphology and the purity of the d eoxidized surface are improved with TDMAAs cleaning. It nas found that additional ex-situ chemical treatments further improve the cleaning. With the proper ex-situ preparation and TDMAAs cleaning, secondary ion mass spectrometry (SIMS) shows the removal of carbon at the regrowth th interface to levels below the residual carbon concentration, while oxygen and silicon impurity concentrations are, respectively 7.8 x 10( 11) cm(-2) and 1.7 x 10(11)cm(-2). The carrier depletion at the regrow th th interface is reduced to 2.6 x 10(11) cm(-2) and contact resistiv ity is lowered to 2.7 x 10(-6) Ohm . cm2.