以固態源分子束磊晶法成長含銻化合物半導體材料與元件

Growth of Sb-containing Compound Semiconductor Materials and Devices by using Solid Source Molecular Beam Epitaxy

劉珀瑋(Po-Wei Liu)

指導教授 ： 林浩雄

國立臺灣大學/電機資訊學院/電機工程學研究所/博士(2004年)

https://doi.org/10.6342/NTU.2004.00624

摘要

本篇論文中研究以固態源分子束磊晶法成長含銻化合物半導體材料與元件。所研究的材料有銻化鎵以及銻砷化鎵/砷化鎵量子井。
在銻化鎵材料的成長方面，使用Applied-EPI Model 175 Standard Cracker for Sb為銻源，在砷化鎵和銻化鎵基板上成長銻化鎵磊晶層。研究銻化鎵磊晶層的成長條件，包括Sb cracker裂解區溫度，成長溫度，Sb/Ga BEP ratio等條件。並成它a成長出銻化鎵磊晶層，以最佳條件成長在銻化鎵基板上的銻化鎵磊晶層其低溫光激螢光譜可解析出自由激子的放光，顯示了磊晶品質的優良。
在銻砷化鎵/砷化鎵量子井的成長方面，嘗試在砷化鎵基板上成長銻砷化鎵/砷化鎵量子井。以固定As/Ga ratio而改變Sb/Ga ratio來控制量子井中銻砷化鎵的成分。成長出的量子井具有良好的光激螢光強度，並證實了其應用在1.3um波段的可行性。之後並且研究了銻砷化鎵/砷化鎵異質結構的帶排列形式。藉由簡單的方法求得此第二型量子井的平帶放光能量。並藉由成長砷化鋁鎵/銻砷化鎵第一型量子井比較其放光能量，以同時擬合得到銻砷化鎵的應變能隙以及銻砷化鎵/砷化鎵、砷化鋁鎵/銻砷化鎵的能帶排列。得到GaAs0.7Sb0.3/GaAs的價電帶不連續比值Qv = 1.14 ± 0.03，Al0.3Ga0.7As/GaAs0.7Sb0.3的Qv = 0.79 ± 0.03，而GaAs0.7Sb0.3的應變能隙為1.00 ± 0.01eV。此外，並研究了長晶時不同五族保護下成長中斷對於銻砷化鎵/砷化鎵量子井光學特性的影響。發現以銻作五族保護成長中斷的樣品其光學特性較佳。而在這些介面處以不同五族保護作成長中斷的樣品的變溫與變激發強度的量測中，發現PL peak與PL FWHM分別會有”S-shape”與”inverse-S shape”的變化特性。部分樣品在低溫時隨著雷射激發必v的增加，其PL FWHM會有變小的現象。這些現象的原因可能來自於局部能階放光與帶間放光的同時存在的影響。銻成分的波動及介面處的不平整可能是局部能階的成因。
在銻砷化鎵/砷化鎵量子井雷射的成長方面，在砷化鎵基板上分別成長了雙量子井與單量子井雷射結構。雙量子井雷射的最低起振電流為210A/cm2，發光波長為1.28um。單量子井雷射的最低起振電流為300A/cm2，發光波長為1.292um。並研究了所成長雷射的量子效率與透明電流密度等特性。銻砷化鎵量子井雷射較差的溫度特性，可能來自於其第二型結構造成較高載子濃度的累積所致。經由研究雷射的自發性放光與電流的特性，發現銻砷化鎵/砷化鎵量子井雷射在室溫時其載子復合機制以放射性復合為主，但到高溫時變成以歐傑復合為主。第二型量子井中較高的載子濃度可能是高溫時歐傑復合速率增加的原因。

關鍵字

分子束磊晶 ； 銻化鎵 ； 含銻化合物半導體 ； 銻砷化鎵

並列摘要

In this dissertation, we studied the growth of Sb-containing compound semiconductor materials and devices by using solid source molecular beam epitaxy (SSMBE). GaSb epilayers and GaAsSb/GaAs quantum wells were investigated.
In the study of GaSb epilayer, high quality GaSb epilayers were successfully grown. Free exciton emissions were observed in the low temperature photoluminescence of the GaSb epilayers grown with the optimized growth parameters.
On the growth of GaAsSb/GaAs quantum wells, GaAsSb/GaAs quantum wells were grown on GaAs substrates. Strong photoluminescence intensity was observed in the grown quantum well. By proposing a simple method to exclude the band bending induced blueshift in power dependent photoluminescence, we firstly deduced the flat-band transition energies in the type-II GaAs/GaAsSb quantum wells.With the combination of the photoluminescence analysis of the type-I AlGaAs/GaAsSb quantum wells, we derived the strained band gap of GaAs0.7Sb0.3, which is 1.00±0.01eV. And the determined valence band offset ratios Qv of GaAs/GaAs0.7Sb0.3 and Al0.3Ga0.7As/GaAs0.7Sb0.3 heterostructures are 1.14±0.03 and 0.79±0.03 respectively. Also, we studied the effect of growth interruption at the interfaces with different group V exposure on the optical quality of the GaAsSb/GaAs quantum well. It is found that samples with Sb protection at the interfaces during growth interruption shows better optical quality. These samples also show “S-shape” and “inverse-S shape” characteristics in the PL peak and PL FWHM dependence on temperature. These phenomenon may be due to the co-exist of the localized state related emissions and band-to-band emissions. Sb composition fluctuation and interface roughness may be the reason for the localized state.
Finally, we successfully grew GaAsSb/GaAs double quantum well and single quantum well laser on GaAs substrates by using SSMBE. The lowest threshold current density is 210A/cm2 and the emission wavelength is 1.28um for the double quantum well laser. The lowest threshold current density is 300A/cm2 and the emission wavelength is 1.292um for the single quantum well laser. By studied the spontaneous emission characteristic of the grown laser, we found that the dominate carrier recombination mechanism is radiative recombination. And as temperature increases, the Auger recombination rate increases and dominates the carrier recombination mechanism. The higher carrier density in the type-II quantum well results in higher Auger recombination rate as temperature increases.

並列關鍵字

GaAsSb ； GaSb ； Sb-containing compound semiconductor ； molecular beam epitaxy

參考文獻

2. H. K. Choi, S. Eglash, “High-Efficiency High-Power GaInAsSb-AlGaAsSb Double-Heterostructure Lasers Emitting at 2.3

1. V. Swaminathan and A. T. Macrander, “Materials Aspects of GaAs and InP Based Structures”, Prentice Hall, New Jersey (1991).