Creating Single Boundary between Two CdTe (111) Wafers with Controlled Orientation by Wafer Bonding

Abstract

Zinc-blende (ZB) CdTe has drawn great attention as optoelectronic and solar energy conversion materials since it has a near optimum band gap of 1.6 eV and a absorption coefficient greater than 5x10 5 /cm. CdTe can be either ZB or wurtzite (WZ) structures, resulting in different electronic properties. It has been reported that the twin superlattice with numerous twin boundaries in III-V and II-VI semiconductor nanowires along growth orientation of ZB structures considerably enhance band gap engineering and mechanical behavior in quasi-one-dimensional materials [1]. This opens new possibilities for properties and functionalities at the atomic and quantum scales by controlling the twin boundary and modulating twin densities. Therefore, it is an in-demand and challenging feat to “create” a single twin boundary in a nanowire or bulk material in order to understand the electronic and mechanical characteristics of the III-V and II-VI quantum well or barrier. Wafer bonding, which enables the direct integration of two or more single crystal wafers with controlled surfaces and orientation, is a key technique in creating a single boundary [2]. In this study, we show the creation of a single boundary between two identical CdTe single crystals.