Electronic structure of the valence band of II--VI wide band gap semiconductor interfaces

TL;DR

This paper investigates the electronic band structure of (001)-CdTe interfaces with other II-VI semiconductors using tight binding models and Green's function methods, revealing complex interface states and their potential impact on transport properties.

Contribution

It provides a detailed analysis of the interface band structure for various II-VI semiconductor combinations, introducing the concept of FISIM states and their behavior at interfaces.

Findings

Interface band structure varies significantly from bulk properties.

Reappearance of surface-induced bulk states at interfaces.

Identification of FISIM states influencing transport.

Abstract

In this work we present the electronic band structure for (001)--CdTe interfaces with some other II--VI zinc blende semiconductors. We assume ideal interfaces. We use tight binding Hamiltonians with an orthogonal basis ($s p^3 s^*$). We make use of the well--known Surface Green's Function Matching method to calculate the interface band structure. In our calculation the dominion of the interface is constituted by four atomic layers. We consider here anion--anion interfaces only. We have included the non common either anion or cation (CdTe/ZnSe), common cation (CdTe/CdSe), and common anion (CdTe/ZnTe) cases. We have aligned the top of the the valence band at the whole interface dominion as the boundary condition. The overall conclusion is that the interface is a very rich space where changes in the band structure with respect to the bulk do occur. This is true not only at interfaces with no common atoms but also at the ones with either common cation or anion atoms irrespective to the fact that the common atomic layers are facing or not each other at the interface. Finally, we found that the (001)--surface--induced bulks states reappear at the interface in contrast to the pure (001)--surface resonances which disappear. This confirm our previous interpretation of such states as {\it bulk} states. Their behaviour is very interesting at the interface. We have refine the terminology for these states to up--date it to the new results and have call them {\it Frontier induced semi--infinite medium} (FISIM) states. They might well appear also in quantum wells and superlattices and have influence in the transport properties of these systems.