Ordering parameter and band-offset determination for ordered Ga x In 1 − x P / ( Al 0.66 Ga 0.34 ) y In 1 − y P quantum wells
Ordering parameter and band-offset determination for ordered Ga x In 1 − x P / ( Al 0.66 Ga 0.34 ) y In 1 − y P quantum wells
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DOI：
10.1103/physrevb.66.035109
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发表时间：
2002-07
影响因子：
3.7
通讯作者：
J. Shao;A. Dörnen;R. Winterhoff;F. Scholz
中科院分区：
文献类型：
--
作者：
J. Shao;A. Dörnen;R. Winterhoff;F. Scholz
用低温(1.8K)光反射率测量了有序${\mathrm{Ga}}_{x}{\mathrm{In}}_{1\ensuremath{-}x}\mathrm{P}/({\mathrm{Al}}_{0.66}{\mathrm{Ga}}_{0.34}{)}_{y}{\mathrm{In}}_{1\ensuremath{-}y}\mathrm{P}$量子阱(QW)样品的主要带间跃迁能。为了考虑有序化对能带偏移和光学跃迁能的影响，将带隙还原$[\ensuremath{\Delta}{E}_{g}(\ensuremath{\eta})]$和价带分裂$[{\ensuremath{\Delta}}_{111}^{O}(\ensuremath{\eta})]$的CuPt型有序化效应引入到模型固体理论中，建立了理论模型。对观测到的跃迁能与计算结果的拟合表明，该模型可以合理地描述有序量子波中的带间跃迁，并得出如下结论：(1)量子波中的有序参数可以用第一个带间跃迁能来估计。(Ii)在文献中可用的数学值中，-0.43 eV/0.16 eV和-0.471 eV/0.20 eV的两个组合$\ensuremath{\Delta}{E}_{g}(1)/{\ensuremath{\Delta}}_{111}^{O}(1)$可以很好地描述晶格匹配的量子波。较小的绝对值$\ensureath{\Delta}{E}_{g}(1)$是有利的。压缩应变会削弱有序化效应。(Iii)对于无序和晶格匹配/压缩应变的量子阱，导带偏移比具有几乎恒定的值${q}_{c}\EnsureMath{\sim}0.58。$(Iv)有序导致${q}_{c}的增加，而对于晶格匹配和压缩应变的量子阱，当从0到1变化时，其价带形变势和导带形变势的取值范围在0.58-0.72$之间。还将${q}_{c}$与之前报告的值进行了比较。
Low-temperature (1.8 K) optical reflectivity measurements have been carried out to identify the principal interband transition energies in ordered ${\mathrm{Ga}}_{x}{\mathrm{In}}_{1\ensuremath{-}x}\mathrm{P}/({\mathrm{Al}}_{0.66}{\mathrm{Ga}}_{0.34}{)}_{y}{\mathrm{In}}_{1\ensuremath{-}y}\mathrm{P}$ quantum well (QW) samples. To account for ordering effects on the band offset and optical transition energy, a theoretical model has been constructed by incorporating the CuPt-type ordering effects of band-gap reduction $[\ensuremath{\Delta}{E}_{g}(\ensuremath{\eta})]$ and valence-band splitting $[{\ensuremath{\Delta}}_{111}^{O}(\ensuremath{\eta})]$ into the model-solid theory. Fitting of the observed transition energies to the calculations indicates that the model can reasonably describe the band-to-band transitions in the ordered QW's. Conclusions are reached that show that (i) ordering parameters in the QW's can be estimated with the first band-to-band transition energy. (ii) Among the $\ensuremath{\Delta}{E}_{g}(1)$ values available in the literature, two combinations $\ensuremath{\Delta}{E}_{g}(1)/{\ensuremath{\Delta}}_{111}^{O}(1)$ of -0.43 eV/0.16 eV and -0.471 eV/0.20 eV lead to good descriptions of the lattice-matched QW's. For the compressively strained samples, however, a smaller absolute value of $\ensuremath{\Delta}{E}_{g}(1)$ is favorable. Compressive strain tends to weaken the ordering effects. (iii) For a disordered and lattice-matched/compressively strained QW, the conduction-band-offset ratio has a nearly constant value of ${Q}_{c}\ensuremath{\sim}0.58.$ (iv) Ordering causes an increase in ${Q}_{c},$ and for lattice-matched and compressively strained QW's ${Q}_{c}$ falls in a range of $0.58\ensuremath{-}0.72$ as $\ensuremath{\eta}$ changes from 0 through 1. The influence is checked by using different values of the valence- and conduction-band deformation potentials in the calculations. A comparison of ${Q}_{c}$ is also made with previously reported values.