Inversion and accumulation layers at InN surfaces

The conduction band minimum (CBM) at the centre of the Brillouin zone (the ΓΓ-point) of wurtzite InN is extremely low compared with the rest of the conduction band-edge. As a result, the charge neutrality level is located high in the conduction band at the ΓΓ-point. This single property of the band structure of InN is the common cause of the observed high unintentional n-type doping, radiation resistance, interface electron accumulation, and inefficiency of p-type doping. Overcoming the challenges and exploiting the opportunities presented by these effects will be critical for future device applications of InN. Here, calculations of charge accumulation and inversion layer profiles at the surfaces of n- and p  -type InN, respectively, are presented and discussed. The nature of the band structure of InN, with its particularly low ΓΓ-point CBM, dictates the existence of positively charged donor-type interface states, leading to electron accumulation at InN interfaces.