Artificial Control of Semiconductor Heterojunction Band Discontinuity

本文用X射线光电子能谱（XPS）和自洽紧束缚计算研究了Si层在GaAs/AlAs结构中的作用。研究发现，要控制异质结能带偏移，必须精确控制硅占据位，形成人工界面偶极子。然而，在目前的实验条件下，插入的Si原子分布在几个原子层上，主要作为施主杂质，这只会引起能带弯曲。或者，我们提出了联合收割机来改变两个间隔很近的δ掺杂层的能带偏移。霍尔测量表明，生长温度改变了仅用Si作为掺杂剂进行δ掺杂的（311）A取向GaAs的导电类型。在GaAs/AlAs异质结构中，掺杂p型和n型硅层的有效带偏移为-0.5eV，掺杂层间距为-5nm。实验表明，通过控制硅原子的位置，可以引入人工界面偶极子来实现对异质结能带偏移的控制。

Roles of Si layr at GaAs/AlAs structures have been studied by x-ray photoemission spectroscopy(XPS) and self-consistent tight-binding calculations. It is found that one has to precisely control the Si-occupying sites to from an artificial interface dipole to control heterojunction band offsets. However, under the present experimental condition, inserted Siatoms distribute over a few atomic layrs and mainly act as donor impurities, which introduce only a band bending.Alternatively, we proposed to combine two closely spaced delta-doping layrs to vary the band offsets. Hall measurements show that a growth temperature varies a conduction type of(311)A-oriented GaAs delta-doped with only Si as a dopant. The effective band offset is varied by -0.5eV at a GaAs/AlAs heterostructure with p-and n-type Si doping sheets with a narrow spacing of -5 nm. This experiment shows that by controlling atomic sites of inserted Si, we can introduce an artificial interface dipole to realize a control of heterojunction band offsets.