Etching of InAs in HCl Gas and Selective Removal of InAs Layer on GaAs in Ultrahigh-Vacuum Processing System

Abstract

The etch rate of InAs in HCl gas is studied for the first time and is found to be far greater than that of GaAs. The complete removal of an InAs layer grown on GaAs was achieved by this etching, resulting in a very flat surface. This is confirmed by the photoluminescence study on a novel GaAs/AlGaAs quantum well (QW), which was prepared by depositing a 50 nm InAs film at the center of the well, and subsequently etching it off before the remainder of the QW was formed. This unique selectivity can be employed to remove an InAs film which is used in the in situ patterning technique of GaAs.

Ultraclean etching of GaAs by HCl gas and in situ overgrowth of (Al)GaAs by molecular beam epitaxy

“…The temperature dependence of GaAs etch rate has been reported elsewhere. 20 For the air-exposure treatment, the sample was once unloaded from the UHV system and exposed to the room air for about 1 h. Then, the sample was reloaded into the system, where the sample was first heated to 620°C in the MBE chamber under arsenic flux for about 10 min, as a thermal cleaning of the surface and an outgassing of the Mo holder. During this step, the Al cell temperature was maintained at 700°C in order to avoid the unexpected adsorption of Al atoms at the surface.…”

“…[12][13][14] On the other hand, the etching of GaAs and InAs by HCl gas has been also studied [15][16][17][18][19][20] and found to exhibit an opposite selectivity between GaAs and InAs to that in Cl 2 gas etching. 20 To date, however, the properties of the etch/ overgrown interfaces have not been fully clarified. The difference between Cl 2 and HCl gases in the reaction process as well as the temperature range used for the etching may result in different interface properties.…”