Gelczuk Łukasz, Kopaczek Jan, Rockett Thomas B O, Richards Robert D, Kudrawiec Robert
Faculty of Microsystem Electronics and Photonics, Wrocław University of Science and Technology, Janiszewskiego 11/17, 50-372, Wroclaw, Poland.
Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370, Wrocław, Poland.
Sci Rep. 2017 Oct 9;7(1):12824. doi: 10.1038/s41598-017-13191-9.
Deep-level defects in n-type GaAs Bi having 0 ≤ x ≤ 0.023 grown on GaAs by molecular beam epitaxy at substrate temperature of 378 °C have been injvestigated by deep level transient spectroscopy. The optical properties of the layers have been studied by contactless electroreflectance and photoluminescence. We find that incorporating Bi suppresses the formation of GaAs-like electron traps, thus reducing the total trap concentration in dilute GaAsBi layers by over two orders of magnitude compared to GaAs grown under the same conditions. In order to distinguish between Bi- and host-related traps and to identify their possible origin, we used the GaAsBi band gap diagram to correlate their activation energies in samples with different Bi contents. This approach was recently successfully applied for the identification of electron traps in n-type GaAs N and assumes that the activation energy of electron traps decreases with the Bi (or N)-related downward shift of the conduction band. On the basis of this diagram and under the support of recent theoretical calculations, at least two Bi-related traps were revealed and associated with Bi pair defects, i.e. (V+Bi) and (As+Bi). In the present work it is shown that these defects also influence the photoluminescence properties of GaAsBi alloys.
通过深能级瞬态谱对在378°C衬底温度下采用分子束外延在GaAs上生长的0≤x≤0.023的n型GaAsBi中的深能级缺陷进行了研究。通过非接触电反射和光致发光研究了这些层的光学性质。我们发现，掺入Bi抑制了类GaAs电子陷阱的形成，因此与在相同条件下生长的GaAs相比，稀释的GaAsBi层中的总陷阱浓度降低了两个数量级以上。为了区分与Bi相关和与主体相关的陷阱并确定其可能的起源，我们使用GaAsBi带隙图将不同Bi含量样品中它们的激活能关联起来。这种方法最近成功应用于识别n型GaAsN中的电子陷阱，并假设电子陷阱的激活能随着导带与Bi（或N）相关的向下移动而降低。基于该图并在最近理论计算的支持下，揭示了至少两个与Bi相关的陷阱，并与Bi对缺陷相关，即（V + Bi）和（As + Bi）。在本工作中表明，这些缺陷也影响GaAsBi合金的光致发光性质。
