Growth of Cd1−<i>x</i>Zn<i>x</i>Te by molecular beam epitaxy

Feldman, R. D.; Austin, R. F.; Dayem, A. H.; Westerwick, E.H.

doi:10.1063/1.97550

Cited by 53 publications

(9 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…XRD rocking curves of the buffer layers and cap layers showed single-crystalline (112) material with linearly graded in-plane and out-of-plane lattice parameters, suggesting fully relaxed buffer layers with final cap compositions close to intended values. As observed in earlier work with nongraded Cd 1ÿ x Zn x Te layers, 10 the XRD rocking curve FWHM of the uniform Cd 1ÿ x Zn x Te cap layers increased with increasing Cd concentration. For x ; 0.2, FWHM could not be measured because the intensity of the (224) reflection peak was below detector limits.…”

Section: Resultssupporting

confidence: 68%

“…10 X-ray diffraction peak half-widths and surface quality were observed to degrade as Cd content was increased from 0% to 80%. 10 Phase separation into Cd-rich (111) and Zn-rich (001) phases was suggested as a possible explanation for this behavior. Chemical vapor deposition (CVD) of Cd 1ÿ x Zn x Te films with 0 x 1 has been reported on (001) GaAs 11 and (001) and (111) Si samples.…”

Section: Introductionmentioning

confidence: 96%

See 1 more Smart Citation

CdZnTe graded buffer layers for HgCdTe/Si integration

Groenert

Markunas

2006

Journal of Elec Materi

View full text Add to dashboard Cite

Section: Resultssupporting

confidence: 68%

Section: Introductionmentioning

confidence: 96%

CdZnTe graded buffer layers for HgCdTe/Si integration

Groenert

Markunas

2006

Journal of Elec Materi

View full text Add to dashboard Cite

“…These superlattices (grown on a GaAs substrate) provide a straightforward control of the effective lattice constant of the system, and thus the strain in the subsequently grown HgTe layers. The use of SLS rather than (Cd,Zn)Te solid solutions for lattice constant control is necessary because solid solutions suffer from poor crystal quality due to phase separation effects [8,9]. We fabricate both tensile (ε < 0) and compressively (ε > 0) strained QWs using coherent epitaxy of (Zn,Cd,Hg)Te -HgTe -(Zn,Cd,Hg)Te heterostructures on virtual substrates.…”

mentioning

confidence: 99%

Strain Engineering of the Band Gap of HgTe Quantum Wells Using Superlattice Virtual Substrates

et al. 2016

View full text Add to dashboard Cite

The HgTe quantum well (QW) is a well-characterized two-dimensional topological insulator (2D-TI). Its band gap is relatively small (typically on the order of 10 meV), which restricts the observation of purely topological conductance to low temperatures. Here, we utilize the strain-dependence of the band structure of HgTe QWs to address this limitation. We use CdTe-Cd0.5Zn0.5Te strained-layer superlattices on GaAs as virtual substrates with adjustable lattice constant to control the strain of the QW. We present magneto-transport measurements, which demonstrate a transition from a semimetallic to a 2D-TI regime in wide QWs, when the strain is changed from tensile to compressive.Most notably, we demonstrate a much enhanced energy gap of 55 meV in heavily compressively strained QWs. This value exceeds the highest possible gap on common II-VI substrates by a factor of 2-3, and extends the regime where the topological conductance prevails to much higher temperatures.The transport properties of molecular-beam epitaxially (MBE) grown HgTe QWs embedded in Cd 0.7 Hg 0.3 Te barriers have attracted considerable attention due to the discovery of the quantum-spin-Hall (QSH) effect in these structures [1][2][3]. The QSH effect is the landmark property of a 2D-TI and is characterized by the presence of a pair of one-dimensional, counter-propagating ("helical") channels along the edges of the mesa, giving rise to a quantized longitudinal conductanceA prerequisite for the formation of edge channels is atopologically nontrivial -inverted band structure, as is present in HgTe QWs when the thickness d QW exceeds d c = 6.3 nm [1]. Inverted HgTe QWs have a relatively small band gap E G (typically lower than 15 meV), which can make it difficult to gate homogeneously into the gap over the whole mesa, and also prevents applications at elevated temperatures. Here we present a way to increase E G well above the thermal energy at room temperature (k B T = 25 meV). This is achieved by applying compressive strain to HgTe QWs through coherent growth on virtual substrates with a freely tunable lattice constant.The crucial influence of strain on the band structure of HgTe has been demonstrated previously for bulk layers (layer thickness d > 40 nm): epitaxy of HgTe on CdTe substrates exerts tensile strain (ε = −0.3 %), which causes a gap-opening of the Γ 8 doublet, transforming the bulk semimetal into a three-dimensional topological insulator [4,5]. However, these previous experiments used commercially available MBE quality substrates, limiting the options to Cd 0.96 Zn 0.04 Te[1-3] and CdTe [4,5][6]. In both cases, the lattice constant of the substrate material is larger than that of HgTe, resulting in a tensile strain in the epilayers. Under such conditions, the largest gaps that can be obtained in inverted QWs are E G = 17 meV and 25 meV for wells grown on CdTe and Cd 0.96 Zn 0.04 Te, respectively [7].The present work reports on a major progress in this situation. We use CdTe-Cd 0.5 Zn 0.5 Te (001) strainedlayer superlattices (SLS) as virtual ...

show abstract

“…A typical θ-2θ spectrum obtained for a Cd 1-x Zn x Te specimen is shown in Fig. 7 The lattice parameters for all samples were calculated from their respective x-ray spectra, and these values were then used to derive their alloy compositions using Vegard's law. The intense narrow peak on the right represents the (004) reflection from the GaAs substrate, and the peak to the left of it corresponds to Cd 1-x Zn x Te (004) Bragg planes.…”

Section: Mbe Growth and X-ray Resultsmentioning

confidence: 99%