Determination of interface properties between a depleted heteroepitaxial layer and a substrate from capacitance measurements

Abstract

A method for the determination of interface properties between a depleted heteroepitaxial layer and a substrate is presented. The method is based on the measurement of the zero bias capacitance of a metal gate that forms a Schottky contact with the depleted epilayer. The interface charge density can be extracted regardless of the exact values of the energy band discontinuities. A microscopic electrostatic analysis of the interface is presented which takes into account the effects of interface charges and interface dipoles. Experimental results are presented for the case of ZnTe epilayers grown by metal organic chemical vapor deposition on CdTe substrates.

Metal-ferroelectric-metal heterostructures with Schottky contacts. I. Influence of the ferroelectric properties

“…43,44 The present model adapts this previous model to the case of metal-ferroelectric interfaces. The first step in computing the above mentioned quantities is to solve the Poisson equation for the structure presented in Fig.…”

“…If all the sallow impurities are ionized at the given temperature then p(T) = N A and N eff should be replaced by N A in (9). 43,44 We underline that both the shallow acceptors and the deep levels are considered uniformly distributed throughout the film thickness. The non-uniform charge density in the depleted region is only apparent and is dependent on the balance between the concentrations N A and N eff and on the energetic depth of the deep level.…”

Barrier formation at graded HgTe/CdTe heterojunctions

“…The measured ⌬E v of an abrupt HJ also includes the contribution of a dipole layer of charge at the abrupt interface, 10 and hence ⌬E v is not exactly equal to ⌬E vo . Theoretical calculations 19 show that the contribution of the interface dipole layer to the band discontinuity is of the order of 0.1 eV, which is also the experimental error in current state of the art energy band offset measurements.…”

“…20 The dipole layer at the interface which is responsible for the difference between ⌬E v and ⌬E vo also introduces the same amount of discontinuity in the electrostatic potential across the abrupt interface. 10,20 The valence band discontinuity is one of the causes of rectifying behavior that appears in abrupt HgTe/CdTe structures. One of the most important features of the graded heterostructure is the ability to overcome potential barriers caused by band discontinuities.…”

“…͑6͒ is solved numerically as a two boundary conditions problem by the relaxation method. 10 The boundary conditions are the values of E v f far away from the junction, in the neutral regions of both sides.…”