Effects of the host conduction band energy on the electronic band structure of ZnCdTeO dilute oxide alloys

M. Welna; L. Janicki; W. M. Linhart; T. Tanaka; K. M. Yu; R. Kudrawiec; W. Walukiewicz

doi:10.1063/1.5111600

Effects of the host conduction band energy on the electronic band structure of ZnCdTeO dilute oxide alloys

M. Welna^*, L. Janicki, W. M. Linhart, T. Tanaka, K. M. Yu, R. Kudrawiec, W. Walukiewicz

^*Corresponding author for this work

Department of Physics

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

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Abstract

Interband optical transitions in highly mismatched ZnTe_1-xO_x and Zn_1-yCd_yTe_1-xO_x alloys with Cd content y = 0.1 and 0.32 and oxygen content x < 0.016 grown on ZnTe substrates were studied by photoreflectance (PR) and photoluminescence (PL) in a broad temperature range. The incorporation of oxygen into a Zn(Cd)Te matrix results in a splitting of the conduction band (CB) into two E_- and E₊ subbands forming a semiconductor with an intermediate band. In ZnTeO, only the E_- band could be probed by PR and there was no PL signal. An addition of Cd atoms to form a ZnCdTeO quaternary alloy significantly improves the optical quality as evidenced by an emergence of an E₊ related transition in the PR spectra and the appearance of a PL emission related to the E_- band visible up to 260 K. Moreover, for Cd content above 25%, a change in the E_- band character is observed from localized O-like to CB-like. The analysis of a PR signal shows a strong reduction of the temperature dependence of the energy gap of Zn(Cd)TeO alloys compared to ZnTe. The temperature related reduction of the bandgap shift with increasing O content is well explained by the band anticrossing interaction between the temperature dependent conduction band of the host Zn(Cd)Te matrix and the temperature independent energy of highly localized O states.

Original language	English
Article number	083106
Journal	Journal of Applied Physics
Volume	126
Issue number	8
Online published	26 Aug 2019
DOIs	https://doi.org/10.1063/1.5111600
Publication status	Published - 28 Aug 2019

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COPYRIGHT TERMS OF DEPOSITED FINAL PUBLISHED VERSION FILE: This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in M. Welna, Ł Janicki, W. M. Linhart, T. Tanaka, K. M. Yu, R. Kudrawiec, and W. Walukiewicz, "Effects of the host conduction band energy on the electronic band structure of ZnCdTeO dilute oxide alloys", Journal of Applied Physics 126, 083106 (2019) and may be found at https://doi.org/10.1063/1.5111600.

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title = "Effects of the host conduction band energy on the electronic band structure of ZnCdTeO dilute oxide alloys",

abstract = "Interband optical transitions in highly mismatched ZnTe1-xOx and Zn1-yCdyTe1-xOx alloys with Cd content y = 0.1 and 0.32 and oxygen content x < 0.016 grown on ZnTe substrates were studied by photoreflectance (PR) and photoluminescence (PL) in a broad temperature range. The incorporation of oxygen into a Zn(Cd)Te matrix results in a splitting of the conduction band (CB) into two E- and E+ subbands forming a semiconductor with an intermediate band. In ZnTeO, only the E- band could be probed by PR and there was no PL signal. An addition of Cd atoms to form a ZnCdTeO quaternary alloy significantly improves the optical quality as evidenced by an emergence of an E+ related transition in the PR spectra and the appearance of a PL emission related to the E- band visible up to 260 K. Moreover, for Cd content above 25%, a change in the E- band character is observed from localized O-like to CB-like. The analysis of a PR signal shows a strong reduction of the temperature dependence of the energy gap of Zn(Cd)TeO alloys compared to ZnTe. The temperature related reduction of the bandgap shift with increasing O content is well explained by the band anticrossing interaction between the temperature dependent conduction band of the host Zn(Cd)Te matrix and the temperature independent energy of highly localized O states.",

author = "M. Welna and L. Janicki and Linhart, {W. M.} and T. Tanaka and Yu, {K. M.} and R. Kudrawiec and W. Walukiewicz",

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T1 - Effects of the host conduction band energy on the electronic band structure of ZnCdTeO dilute oxide alloys

AU - Welna, M.

AU - Janicki, L.

AU - Linhart, W. M.

AU - Tanaka, T.

AU - Yu, K. M.

AU - Kudrawiec, R.

AU - Walukiewicz, W.

PY - 2019/8/28

Y1 - 2019/8/28

N2 - Interband optical transitions in highly mismatched ZnTe1-xOx and Zn1-yCdyTe1-xOx alloys with Cd content y = 0.1 and 0.32 and oxygen content x < 0.016 grown on ZnTe substrates were studied by photoreflectance (PR) and photoluminescence (PL) in a broad temperature range. The incorporation of oxygen into a Zn(Cd)Te matrix results in a splitting of the conduction band (CB) into two E- and E+ subbands forming a semiconductor with an intermediate band. In ZnTeO, only the E- band could be probed by PR and there was no PL signal. An addition of Cd atoms to form a ZnCdTeO quaternary alloy significantly improves the optical quality as evidenced by an emergence of an E+ related transition in the PR spectra and the appearance of a PL emission related to the E- band visible up to 260 K. Moreover, for Cd content above 25%, a change in the E- band character is observed from localized O-like to CB-like. The analysis of a PR signal shows a strong reduction of the temperature dependence of the energy gap of Zn(Cd)TeO alloys compared to ZnTe. The temperature related reduction of the bandgap shift with increasing O content is well explained by the band anticrossing interaction between the temperature dependent conduction band of the host Zn(Cd)Te matrix and the temperature independent energy of highly localized O states.

AB - Interband optical transitions in highly mismatched ZnTe1-xOx and Zn1-yCdyTe1-xOx alloys with Cd content y = 0.1 and 0.32 and oxygen content x < 0.016 grown on ZnTe substrates were studied by photoreflectance (PR) and photoluminescence (PL) in a broad temperature range. The incorporation of oxygen into a Zn(Cd)Te matrix results in a splitting of the conduction band (CB) into two E- and E+ subbands forming a semiconductor with an intermediate band. In ZnTeO, only the E- band could be probed by PR and there was no PL signal. An addition of Cd atoms to form a ZnCdTeO quaternary alloy significantly improves the optical quality as evidenced by an emergence of an E+ related transition in the PR spectra and the appearance of a PL emission related to the E- band visible up to 260 K. Moreover, for Cd content above 25%, a change in the E- band character is observed from localized O-like to CB-like. The analysis of a PR signal shows a strong reduction of the temperature dependence of the energy gap of Zn(Cd)TeO alloys compared to ZnTe. The temperature related reduction of the bandgap shift with increasing O content is well explained by the band anticrossing interaction between the temperature dependent conduction band of the host Zn(Cd)Te matrix and the temperature independent energy of highly localized O states.

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JO - Journal of Applied Physics

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Effects of the host conduction band energy on the electronic band structure of ZnCdTeO dilute oxide alloys

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Effects of the host conduction band energy on the electronic band structure of ZnCdTeO dilute oxide alloys

Abstract

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GRF: Energy Band Engineering for Low Cost Photovoltaics with Abundant Materials

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