One-step synthesis of composite thin film with ZnSe and PbTeSe ternary solid solution

Seishi Abe

doi:10.1007/s40243-015-0060-y

Abstract

This study investigates one-step synthesis of composite thin film with ZnSe and PbTeSe ternary solid solution using hot-wall deposition (HWD) with multiple resources of PbTe and ZnSe. HWD consists of three electric furnaces, designated as wall, source-1, and source-2. The PbTe and ZnSe sources were located in the source-2 and source-1 furnaces for simultaneous evaporation to a glass substrate (Corning Eagle 2000). The substrate temperature was changed by circulating water controlled at temperatures of 340–274 K. X-ray diffraction indicates that composite thin films contain ZnSe with zinc-blende structure and PbTeSe ternary solid solution with NaCl structure. The Raman spectrum also suggests formation of ZnSe without alloying with Pb or Te. The lattice constant of the ternary solid solution gradually increases with increasing source temperature of PbTe. High-resolution transmission electron microscopy indicates that the ternary solid solution forms isolated nanocrystals of 16–30 nm in the composite thin film. Therefore, composite thin films are composed of PbTeSe ternary solid solution nanocrystals embedded in a ZnSe matrix.

Highlights

Composite thin film with semiconductor nanocrystals embedded in a matrix has a potential application for quantum dot solar cells [1]
This study investigates one-step synthesis of composite thin film with ZnSe and PbTeSe ternary solid solution using hot-wall deposition (HWD) with multiple resources of PbTe and ZnSe
The PbTe and ZnSe sources were located in the source-2 and source-1 furnaces for simultaneous evaporation to a glass substrate (Corning Eagle 2000)

Summary

Introduction

Composite thin film with semiconductor nanocrystals embedded in a matrix has a potential application for quantum dot solar cells [1]. Semiconductor nanocrystals provide a shift in optical absorption edge due to quantum size effects, capable of tuning an optical gap to effective energy region for absorbing visible and near infrared light in solar radiation spectrum [2–9]. In the PbSeZnSe system in thermal equilibrium, the mutual solubility range is quite narrow (less than 1 mol%) at temperatures below 1283 K [11] This system phase-separates in a composite and provides compositional steepness at the hetero-interface between PbSe and ZnSe. In addition, a composite thin film of PbSe nanocrystal embedded in a ZnSe matrix is capable of exhibiting quantum size effects because of the relatively large exciton Bohr radius of 46 nm in PbSe [12] and the relatively larger band gap difference between ZnSe (2.67 eV) [13] and PbSe (0.27 eV) [14].

Results and discussion

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Conclusions