摘要
采用分子束外延 (MBE)技术 ,在 Ga As(1 0 0 )衬底上生长了厚度从 0 .0 4 5到 1 .4μm的 Zn Se薄膜 .X射线衍射谱证实 ,随着薄膜厚度的增加 ,应变逐步弛豫 .测量了低温下样品的反射谱和光致发光谱 ,观察到轻重空穴的能级在不同应变下的分裂、移动和反转 ,以及激子极化激元 (Po-lariton)对反射谱的影响 .也观察到束缚激子发光随着薄膜厚度的变化规律 :束缚在中性受主杂质上的束缚激子发光 (I1峰 )随着薄膜厚度的增加逐渐变弱直至消失 ,而束缚在中性施主杂质上的束缚激子发光 (I2 峰 )则随着厚度增加逐渐增强 .
ZnSe films with thickness from 0.045 to 1.4μm were grown on GaAs(100) substra t es. The X-ray diffraction spectra indicate that the strain in the film relaxes w ith the increase of the film thickness. The energy split, shift, and reversion o f the heavy and light hole excitons are observed in the low temperature reflecta nce and photoluminescence(PL) spectra. The properties of the bound exciton PL ar e also found to change with the film thickness. Acceptor-bound-exciton line ( I\-1) is dominated in the PL spectra of the thinnest film. Its intensity dec reases gradually with the increase of film thickness. Meanwhile, an enhancement of neutral-donor-bound-exciton line (I 2) with the film thickness is obser ved.
基金
国家自然科学基金资助项目 !(批准号 :6952 540 8
1 9874 0 1 3)&&
