回顾了近10年基于半导体中量子限制效应红外探测器的进展.主要关注的是二维限制结构,即量子阱结构,形成的区别与传统红外光子探测的子带跃迁机理.在红外光电子领域作为新族的量子阱红外探测器(quantum well infrared photo-detector,QWIP)与最典型的红外探测器代表碲镉汞红外探测器进行了各自特色的分析,包括基本工作机理和材料与器件的制备技术等方面.对于QWIP发展的回顾提升了与碲镉汞红外探测器之间的互补关系.也给出了对于QWIP在未来发展方面的基本趋势.
Quantum well intermixing techniques modify the geometric shape of quantum wells to allow postgrowth adjustments.The tuning effect on the optical response property of a GaAs/AlGaAs quantum well infrared photodetector(QWIP) induced by the interdifussion of Al atoms was studied theoretically.By assuming an improvement of the heterointerface quality and an enhanced Al interdiffusion caused by postgrowth intermixings,the photoluminescence spectrum shows a blue-shifted,narrower and enhanced photoluminescence peak.The infrared optical absorption spectrum also shows the expected redshift of the response wavelength.However,the variation in the absorption peak intensity depends on the boundary conditions of the photo generated carriers.For high-quality QWIP samples,the mean free path of photocarriers is long so that the photocarriers are largely coherent when they transport across quantum wells.In this case,the enhanced Al interdiffusion can significantly degrade the infrared absorption property of the QWIP.Special effects are therefore needed to maintain and/or improve the optical properties of the QWIP device during postgrowth treatments.
The staggered InGaN quantum well (QW) structure and the conventional InGaN QW structure for the emission at a particu-lar wavelength of 400 nm are designed and theoretically investigated,including the distribution of the carriers’ concentration,the radiative recombination rate,the Shockley-Read-Hall (SRH) recombination rate as well as the output performance and the internal quantum efficiency. The theoretical result indicates that the staggered QW structure offers significant improve-ment of carriers’ concentration in the QW,especially the hole concentration. The output power and the internal quantum efficiency also show 32.6 % and 32.5 % enhancement,respectively,in comparison with that of the conventional InGaN QW structure. The reduction of the electron overflow can be the main factor for the improvement of the optical perfor-mance for novel staggered InGaN QW structure.
