锗硅量子阱异质界面附近缺陷研究

Interfacial Defects in Si_1-xGe_x/Si Quantum Wells Detected by Deep Level Transient Spectroscopy

用深能级瞬态谱（ＤＬＴＳ）研究了量子阱样品价中载流子的热发射和异质界面附近的深能级缺陷，得到Ｓｉ０．６７Ｇｅ０．３３／Ｓｉ单量子样品的能带偏移为０．２４ｅＶ．量子阱异质界面附近高浓度的深能级缺陷在样品的ＤＬＴＳ谱上形成一少于峰，该信号只有当测量的脉冲宽度足够大时才能检测到．对比不；司组分相同结构的多量子阱样品发现，组分大时异质界面的深能级缺陷浓度大，因此它可能是失配应变或位错引起的．相应的光致发光谱（ＰＬ）测试结果表明该深能级缺陷还会导致ＰＬ谱中合金层的带边激子峰的湮灭．

Abstract The carrier emission processes from the quantum wells and from the deep level defects have been identified in the deep level transient spectroscopy (DLTS) measurements. The emissions from quantum wells contribute to a majority carrier peak, from which the valence band offset is derived. For Si0.67Ge0.33/Si, our experimental result is 0.24eV. The emission of carriers from high density of defects near the heterointerface gives rise to a minority carrier signal in DLTS, which could be detected only by using injection pulse with relatively large pulse width. The density of interfacial defects varies with Ge composition. The misfit strain or the dislocations may be responsible for the formation of interfacial defects. These defects may quench the near band-edge luminescence in SiGe/Siquantum wells.