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Valence band-anticrossing in GaP$_{1-x}$Bi$_{x}$ dilute bismide alloys: giant bowing of the band gap and spin-orbit splitting energy
| Content Provider | Semantic Scholar |
|---|---|
| Author | Bushell, Zoe L. Broderick, Christopher A. Nattermann, Lukas Joseph, Rita M. Keddie, Joseph L. Rorison, Judy Megan Volz, Kerstin Sweeney, Stephen J. |
| Copyright Year | 2017 |
| Abstract | Using spectroscopic ellipsometry measurements on GaP$_{1-x}$Bi$_{x}$/GaP epitaxial layers up to $x = 3.7$% we observe a giant bowing of the direct band gap ($E_{g}^{\Gamma}$) and valence band spin-orbit splitting energy ($\Delta_{\textrm{SO}}$). $E_{g}^{\Gamma}$ ($\Delta_{\textrm{SO}}$) is measured to decrease (increase) by approximately 200 meV (240 meV) with the incorporation of 1% Bi, corresponding to a greater than fourfold increase in $\Delta_{\textrm{SO}}$ in going from GaP to GaP$_{0.99}$Bi$_{0.01}$. The evolution of $E_{g}^{\Gamma}$ and $\Delta_{\textrm{SO}}$ with $x$ is characterised by strong, composition-dependent bowing. We demonstrate that a simple valence band-anticrossing model, parametrised directly from atomistic supercell calculations, quantitatively describes the measured evolution of $E_{g}^{\Gamma}$ and $\Delta_{\textrm{SO}}$ with $x$. In contrast to the well-studied GaAs$_{1-x}$Bi$_{x}$ alloy, in GaP$_{1-x}$Bi$_{x}$ substitutional Bi creates localised impurity states lying energetically within the GaP host matrix band gap. This leads to the emergence of an optically active band of Bi-hybridised states, accounting for the overall large bowing of $E_{g}^{\Gamma}$ and $\Delta_{\textrm{SO}}$ and in particular for the giant bowing observed for $x \lesssim 1$%. Our analysis provides insight into the action of Bi as an isovalent impurity, and constitutes the first detailed experimental and theoretical analysis of the GaP$_{1-x}$Bi$_{x}$ alloy band structure. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://arxiv.org/pdf/1710.08995v1.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
