In situ characterisation of III–V substrate oxide desorption by surface photoabsorption in MOVPE

The thermal desorption of the oxides of several III–V substrate materials has been investigated by surface photoabsorption (SPA). GaAs, GaSb and InSb substrates were slowly heated to desorb surface oxides. SPA was performed by probing these surfaces with p-polarised 633 nm radiation and constantly monitoring the reflected beam intensity. Such an arrangement allows the oxide desorption to be observed clearly, non-invasively and continuously. The effect of oxidation conditions is explored and temperatures for the deoxidation of GaAs, GaSb and InSb substrates are estimated.