Far-infrared reflectivity spectroscopy of cuprous chloride, cuprous bromide and their mixed crystals

Abstract

The temperature dependence of the far-infrared reflectivity spectrum of CuCl, CuBr and CuCl1 - x Brx , in the zinc-blende structure, is reported over a wide temperature range (10-300 K). The analysis of the experimental data proves the activity of two polar lattice modes in both CuCl and CuBr: the expected lattice mode labelled and an additional lattice mode labelled . The present work displays, for the first time, the activity of three lattice modes in the far-infrared reflectivity spectrum of CuCl1 - x Brx , from room temperature down to liquid helium temperature. Side-bands due to two-phonon processes are observed in the low-frequency range of the reflectivity spectrum of both pure and mixed crystals. The phonon anomalies observed in both pure and mixed crystals are discussed and explained in agreement with the off-centre model.

Impact on structural, optical and electrical properties of CuCl by incorporation of Zn for n-type doping

“…Over the past decade or so, research on the cuprous halides has focussed on three main areas: (1) Spectroscopic and theoretical studies of band structures and excitonic-based luminescence in CuCl, CuBr and copper halide-mixed crystals [5][6][7], (2) fundamental photoluminescence (PL) and spectroscopic studies of CuCl quantum dots embedded in NaCl crystals [8,9] and glass matrices [10,11], (3) surface studies of the growth mechanisms involved in the heteroepitaxy of CuCl single crystals on a number of substrates such as MgO (0 0 1) and CaF 2 (1 1 1) [12], reconstructed (0 0 0 1) haematite (a-Fe 2 O 3 ) [13] and both Si and GaAs [14]. We have previously demonstrated a simple electroluminescent device (ELD) structure based on the deposition of CuCl on Si [15].…”

Room-temperature ultraviolet luminescence from γ-CuCl grown on near lattice-matched silicon

“…Research on the cuprous halides has focused on three main thrusts over the past decade: ͑1͒ spectroscopic and theoretical studies of band structures and excitonic-based luminescence in CuCl and CuBr, [27][28][29][30][31] ͑2͒ fundamental photoluminescence studies of CuCl quantum dots/nanocrystals embedded in NaCl crystals, [32][33][34] and ͑3͒ fundamental surface studies of the growth mechanisms involved in the heteroepitaxy of CuCl single crystals on a number of substrates. [35][36][37][38][39][40] One group of researchers has examined the surface growth mechanisms in the heteroepitaxy of CuCl on both Si and GaAs substrates by molecular-beam epitaxy.…”

“…The cuprous halides, e.g., CuCl, CuBr, and CuI, are ionic I-VII compounds with the zinc-blende ͑T d 2 and F43m͒ structure 29,36 at room temperature. 31,41 At room temperature, the prevalent phase of CuCl is called ␥-CuCl, which is a direct band-gap cubic semiconductor, with a band gap of E G = 3.395 eV ͑ ϳ 365 nm-blue/violet light͒ and a lattice constant a CuCl = 0.541 nm.…”