新型蓝绿发光材料Znse/BeTe超晶格的能带剪裁

Energyband Tailoring for New Blue/Green Light-emitting Material ZnSe/BeTe Superlattice

由于器件的快速退化，101.5小时似乎成了Znse基蓝绿色半导体激光器难于逾越的寿命极限。分析退化机制，发现在强电流注入的半导体激光器中，热退化具有重要影响。研究表明，用作载流子限制层的宽带Ⅱ-Ⅵ族四元合金（如ZnMgSSe）只能对ZnSe中的电子有效地限制，无法对空穴很好地限制;而对BeTe，却只能对空穴进行有效的限制，无法对电子很好地限制。这导致ZnSe（或BeTe）活性层空穴（或电子）漏电发热，引起退化。本文提出以ZnSe／BeTe超晶格为蓝绿发光层，并用包络函数理论具体计算了阱宽、垒宽对载流子能级的不同影响，考察了ZnSe、BeTe厚度比和超晶格周期对带隙、载流子限制能力的调节。为研制新型长寿命蓝绿色半导体激光器提供了一条新的途径。

A lifetime of 101.5 hours, the high limit seems difficult for ZnSe based blue/green laser diodes to step over due to the rapid degradation. It is found, from the analyzing of degradation mechanisims, that heat degradation plaes an important role in a semiconductor laser diode, into which the carriers are strongly poured. Previous results show that, widegap Ⅱ-Ⅵ quaternaries(such as ZnMgSSe) can effectively confine electron in ZnSe only, and supply few hole confinement; for BeTe, the case is just reverse, the quaternaries can confine holes but hardly electrons. The confillement difficulty gives rise to considerable hole(or electron)leakage current in ZnSe(or BeTe), which cause the devices quite hot and quickly degrade. To restrain the leakage current in devices, we give out a proposal here to have ZnSe/BeTe superlattice as blue/green active layer. In the frame of envelope function theory, we study the different effects of well-width and barrier-width on the subband of carriers, and come to a conclusion that, in order to adjust energy gap and carrier confinement ability, we can just adjust the ratio of the thickness of ZnSe to that of BeTe and superlattice period. Thus we suggest a new path to fabricate long lifetime blue/green laser diodes.