The 44th Research Institute of China Electronics Technology Group Corporation
我们利用分子外延技术在(100)和(113)B GaAs衬底上进行了有/无AlAs盖帽层量子点的生长。测量了其在4-100 K温度区间的PL发光光谱。通过对PL光谱的积分强度、峰值能量和半高宽进行分析进而研究了载流子的热传输特性。无AlAs盖帽层的(113)B面量子点的PL光谱的热淬灭现象可以由载流子极易从量子点向浸润层逃逸来解释。然而,有AlAs盖帽层的(113)B量子点的PL热淬灭主要是由于载流子进入了量子点与势垒或者浸润层的界面中的非辐射中心引起的。并且其PL的温度依存性与利用Varshni定律计算的体材料InAs的温度依存性吻合很好,表明载流子通过浸润层进行传输受到了抑制,由于AlAs引起的相分离机制(113)B量子点的浸润层已经消失或者减小了。(100)面有AlAs盖帽层的PL半高宽的温度依存性与无AlAs盖帽层的量子点大致相同,表明相同外延条件下相分离机制在(100)面上不如(113)B面显著。
We have measured the temperature dependence photoluminescence (PL) of quantum dots (QDs) with/without AlAs cap grown on (113)B and (100) GaAs substrates. The carrier thermal transfer was investigated by analyzing the integrated intensity, peak energy, and FWHM of PL spectra. For QDs grown on (113)B GaAs without AlAs cap, PL quenching can be explained as carriers are easily escape from QDs to WL. However, for QD grown on (113)B GaAs with AlAs, the carriers might escape out of the QDs into non-radiation centres in the QD-WL layer or QD-barrier interface. Temperature dependence PL peak energy of QD close to the temperature dependence of bulk InAs band gap, suggesting that the carriers transfer through WL has been inhibited since the WL was removed or reduced due to phase separation by AlAs cap. For QDs with AlAs cap grown on (100) GaAs, similar FWHM dependence to QD without AlAs cap were observed, indicating that the reduction of WL due to phase separation by AlAs might not as effective as that of (113)B GaAs.