Comparison of methods to quantify interface trap densities at dielectric/III-V semiconductor interfaces

Methods to extract trap densities at high-permittivity (k) dielectric/III-V semiconductor interfaces and their distribution in the semiconductor band gap are compared. The conductance method, the Berglund intergral, the Castagń-Vapaille (high-low frequency), and Terman methods are applied to admittance measurements from metal oxide semiconductor capacitors (MOSCAPs) with high- k/ In0.53 Ga0.47 As interfaces with different interface trap densities. The results are discussed in the context of the specifics of the In _0.53 Ga_0.47 As band structure. The influence of different conduction band approximations for determining the ideal capacitance-voltage (CV) characteristics and those of the MOSCAP parameters on the extracted interface trap density are investigated. The origins of discrepancies in the interface trap densities determined from the different methods are discussed. Commonly observed features in the CV characteristics of high- k/ In _0.53 Ga_0.47 As interfaces are interpreted and guidelines are developed to obtain reliable estimates for interface trap densities and the degree of Fermi level (un)pinning for high- k/ In0.53 Ga0.47 As interfaces.