Evolution of electron states at a narrow-gap semiconductor surface in an accumulation-layer formation process
Evolution of electron states at a narrow-gap semiconductor surface in an accumulation-layer formation process
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DOI：
10.1103/physrevb.66.205309
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发表时间：
2002-11
影响因子：
3.7
通讯作者：
Shuma Abe;T. Inaoka;M. Hasegawa
中科院分区：
文献类型：
--
作者：
Shuma Abe;T. Inaoka;M. Hasegawa
在掺杂半导体表面上的吸附通常会导致在表面逐渐形成载流子累积层。在充分考虑InAs和InSb等窄禁带半导体的非抛物线(NP)导带色散的情况下，我们研究了在积累层形成过程中表面电子态的演化。在局域密度泛函理论中引入了NP导带。我们比较了带边有效质量的NP色散和抛物线(P)色散的计算结果。随着累加载流子密度的增加，NP导带的累加载流子开始比P导带的累加载流子更靠近表面。随着{N}_{S}的增大，几个最低子带的底部相继降到费米能级以下，非抛物性开始对每个子带的色散和底部产生很大的影响，特别是对最低子带的色散和底部的影响。为定量研究堆积层形成过程中的表面电子激发提供了数值依据。
Adsorption on a doped semiconductor surface often induces a gradual formation of a carrier-accumulation layer at the surface. Taking full account of a nonparabolic (NP) conduction-band dispersion of a narrow-gap semiconductor, such as InAs and InSb, we investigate the evolution of electron states at the surface in an accumulation-layer formation process. The NP conduction band is incorporated into a local-density-functional formalism. We compare the calculated results for the NP dispersion with those for the parabolic (P) dispersion with the band-edge effective mass. With increase in the accumulated carrier density ${N}_{S},$ the accumulated carriers for the NP conduction band start to be more localized in closer vicinity to the surface than those for the P one. As the bottoms of a few lowest subbands drop below the Fermi level one after another with increase in ${N}_{S},$ the nonparabolicity begins to have a great influence on the dispersion and the bottom of each of these subbands, particularly on those of the lowest subband. The present work provides a numerical basis for making a quantitative examination of surface electronic excitations in the accumulation-layer formation process.