二氧化矽薄膜所誘發之選擇性混合效應對砷化銦鎵量子井之影響

Abstract

本論文致力於研究介電薄膜所誘發之選擇性量子井混合效應。我們將砷化銦鎵量子井異質結構之樣品，鍍上二氧化矽或二氧化鈦薄膜，利用高溫快速熱退火引發量子井混合效應，並量測低溫之激發光譜，以探討其光學性質。經由900 ℃ 高溫快速熱退火之處理，二氧化矽薄膜能增強砷化銦鎵量子井之混合效應，其能量藍移現象可高達100 meV；相對之下，二氧化鈦薄膜對於砷化銦鎵量子井之混合效應展現抑制的效果，產生9.5 meV之能量紅移現象。此外，我們更在二氧化矽薄膜上設計次微米大小之圓形圖樣，藉以誘發部分選擇性量子井混合。圖樣之大小與激發光源之強度，皆會影響部分選擇性量子井混合效應，並可由其對應之低溫激發光譜觀察出趨勢。我們推論，在每個退火溫度條件下，皆有其相對應之特定最小有效直徑；並從能量空間及實際空間的觀點分析電子分佈，進一步解讀不同激發光源強度下之低溫激發光譜。

In this thesis, we aimed at investigating the selective area quantum well intermixing induced by dielectric capping layers. The InGaAs/GaAs quantum well heterostructures were capped with SiO2 and TiO2 films, and high-temperature rapid thermal annealing was applied subsequently. The optical properties were examined by measuring photoluminescence and micro-photoluminescence spectra at 77 K. When the rapid thermal annealing was processed at 900 ℃, an energy blue-shift as large as 100 meV was observed from the SiO2-enhanced quantum well intermixing, and a meaningful energy red-shift of 9.25 meV was offered with the help of TiO2 as an inhibitor of the thermal-induced atomic interdiffusion. Furthermore, the patterns with circular apertures which are sub-micrometer in diameter were fabricated on the SiO2 capping layers as masks. From the aperture-dependent micro-PL spectra, we suggest that the minimum effective diameter of apertures is limited to a specific value for each RTA temperature. We also demonstrated the distribution of electrons from the points of view both in the real space and in the energy space so as to explain the excitation power-dependent transformation of emission peaks. The controllable selective area InGaAs/GaAs quantum well intermixing was successfully accomplished on the sub-micrometer scale with the assistance of patterned SiO2 capping layer, and this would pave a way to realize the monolithic integration of optoelectronic devices.