氮化鎵光學深層能階與砷化銦量子點量測

Abstract

本論文利用光調制反射光譜(phtorefectance，PR)來研究三五族氮化物的深層能階，順利得到在室溫下的放射時間常數。並且探討實驗中遇到因雷射光束的寬度造成量測上的困難與解決方法。在蕭基接面特性較差的樣品，此法提供了一種不錯的非破壞性量測。 InAs/GaAs的量子點發光波長在1.3um左右，是相當適合光纖通訊的重要材料。然而要詳細了解量子點的特性必須知道其能階的位置。用光調制反射光譜可以很輕易的看出其激發態能階的分佈。這些能階分佈的資訊正可提供給量子點的研究更進一步的分析。

Photoreflectance (PR) spectroscopy is an optical and non-destructive technique and is widely used to characterize electronic properties of semiconductor materials and structures. We applied PR technique to measure the time constant deep level transient response by analyzing the PR spectrum amplitude versus the modulation frequency. The hetero-structure of InAs/GaAs quantum dots has a relatively large conduction-band offset and is a suitable material for long wavelength laser diode (about 1.3 μm). In this thesis, the electronic states of InAs/GaAs strain quantum wells and quantum dots were investigated by using photoluminescence (PL) and photoreflectance methods. Both spectroscopic techniques give comparable spectrum features for the same quantum-confined structures.