臺灣博碩士論文加值系統

光調制反射光譜﹙photoreflectance；PR﹚為光學的量測技術，故可用來量測高阻值的材料。本研究即是以此方法對低溫砷化鎵做深層能階的量測，利用PR技術測量分析各種溫度下樣品深層能階的時間常數，據此繪得阿瑞尼斯圖，而可分析得深層能階的游離能及載子捕捉截面積。對以分子束磊晶技術﹙MBE﹚低溫﹙250 ﹚成長的GaAs樣品分析，我們獲得其深層能階到傳導帶的游離能分別為0.0587eV、0.591eV及0.657eV，根據一些相關的文獻可知，0.591eV的深層能階可歸自於砷的沈積﹙precipitate﹚，而0.657eV的深層能階可能是由於砷的錯位﹙antisite﹚所造成，0.0587eV的深層能階尚未見諸文獻，而我們以PR技術卻可明顯地檢測分析獲得，這樣的結果，顯示PR測量技術除了具有非破壞性的先天優點，又有較諸其他深層能階量測技術更強檢測能力的應用潛力。

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 method to measure the deep levels of low-temperature grown GaAs samples. By analyzing the transient response of PR spectrum amplitude to the modulation frequence, we can acquire the time constants of deep levels at various sample temperatures. The Arrhenius plot relating the measured time constants and sample temperatures provides the information of the ionization energies and carrier-capture cross-section areas of deep levels. In this study, we characterize the deep levels of GaAs grown at 250 by molecular beam epitaxy (MBE) technique. By using this optical deep level transient spectroscopy (DLTS) technique, we found three deep levels along with the sample. The ionization energies of these deep levels are 0.657, 0.591, and 0.0587eV, respectively. The deep levels with 0.591 and 0.657eV ionization energies are attributed to the As precipitation and As antisite in the low-temperature GaAs sample, respectively. The 0.0587eV-related deep level has not yet been reported in the literature. Although the factor causing this deep level was not analyzed , we are confident on the validity of our measurement data which are partially consistent with possible known data. In summary, we demonstrated the versatile power of PR technique to characterize the electronic properties of semiconductors. By using the PR technique to perform the optical DLTS, we found some special deep level which was not be identified by other conventional DLTS system.

目 錄
中文摘要…………………………………………………………………i
英文摘要…………………………………………………………………ii
誌謝……………………………………………………………………iii
目錄…………………………………………………………………iv
圖目錄…………………………………………………………………vi
第一章 緒 論………………………………………………………..1
第二章 光調制反射光譜……………………………………………..3
2.1光調制反射光譜技術……………………………….3
2.2調制光譜與介電函數之關係………………..……...4
2.3光調制反射光譜的基本配備……………………….8
2.4以PR量測深層能階之游離能…………………....10
第三章 實驗儀器與量測方法………………………………………17
3.1實驗儀器…………………………………………...17
3.2量測方法…………………………………………...18
3.2.1量測系統………………………………..18
3.2.2電腦量測………………………………..19
第四章 實驗結果與討論……………………………………………22
4.1實驗樣品…………………………………………...22
4.2 與調制頻率之關係………………………22
4.3時間常數與溫度的關係…………………………...24
4.4阿瑞尼斯圖………………………………………...26
第五章 結 論………………………………………………………30
參考文獻…………………………………………………………………31
圖 目 錄
圖 2.1：砷化鎵的反射光譜、波長調制光譜及電場調制光譜
之比較………………………………………………………….33
圖 2.2：光調制前後的能帶圖、離子化雜質濃度分佈圖及內
建電場………………………………………………………….34
圖 2.3：波長調制及電場調制之介電函數虛部的變化……………….35
圖 2.4：a與b之關係圖…………………………………………………36
圖 2.5：SPR與CPR之比較……………………………………………37
圖 2.6：非調制及光調制時的能帶圖………………………………….38
圖 2.7：PR訊號與時間常數及調制頻率的關係。……………………39
圖 2.8：以電腦模擬之 對 的關係圖…………………………40
圖 2.9：GaAs在各個調制頻率之下的PR光譜………………………41
圖 3.1：本CPR系統的方塊圖…………………………………………42
圖 4.1：樣品結果………………………………………………………43
圖 4.2：因光切割器葉片的不同造成 的不連續………………44
圖 4.3：多孔扇葉造成調制光不再是方波……………………………45
圖 4.4：聚焦與否對PR訊號造成的影響……………………………..46
圖 4.5：溫度小於345K，樣品 對 的關係………………….47
圖 4.6：溫度大於380K，樣品 對 的關係……………...…..48
圖 4.7：阿瑞尼斯圖…………………………………………….………49
圖 4.8：由阿瑞尼斯圖判斷系統可量測的深層能階範圍……………50

1. T. C. Lin, T. Okumura, Jpn. J. Appl. Phys. 35, 1630 (1996).
2. S. Shiobara, T. Hashizume, H. Hasegawa, Publication Office, Jpn. J. Appl. Phys. 35, 1159 (1996).
3. Dieter K. Schroder, Semiconductor Material and Device Characterization, John Wiley and Sons (1990).
4. S. M. Sze, Physics of Semiconductor Devices, John Wiley and Sons (1981).
5. Orest J. Glembocki, Fred H. Pollak, SPIE, Vol. 946, 2 (1988).
6. J. L. Shay, Phys. Rev. B 2, 803 (1970).
7. D. E. Aspnes and J. E. Rowe, Phys. Rev. B5, 4022 (1972).
8. Fred H. Pollak, Modulation Spectroscopy of Semiconductors and Semiconductor Microstructures.
9. D. E. Aspnes and J. E. Rowe, Solid State Commun. 8, 1145 (1970).
10. D. E. Aspnes, in M. Balkanski (ed.), Handbook on Semiconductors, Vol. 2, North-Holland, New York, p. 109 (1980).
11. N. Bottka, D. K. Gaskill, R. S. Sillmon, J. of Elec. Materials, Vol. 17, 2, 161 (1988).
12. Surf. Sci., 37, 418 (1973).
13. R. K. Willardson and A. C. Beer, Semiconductors and Semimetals (1972).
14. H. Shen, S. H. Pan, Z. Hang, J. Leng, F. H. Pollak, J. M. Woodall, and R. N. Sacks, Appl. Phys. Lett. 53, 1080 (1988)
15. X. C. Shen, H. Shen, P. Parayanthal, and F. H. Pollak, Superlattice and Microstructures 2, 513 (1986).
16. H. Shen, Z. Hang, S. H. Pan, F. H. Pollak, and J. M. Woodall. Appl. Phys. Lett. 52, 2058 (1988).
17. A. Ksendzov, F. H. Pollak, P. M. Amirtharaj, and J. A. Willson, J. Cryst. Growth 86, 586 (1988).
18. H. Shen, F. H. Pollak, J. W. Woodall, and R. N. Sacks, J. Vac. Sci. Technol B7, 804 (1989)
19. R. E. Nahory and J. L. Shay, Phys. Rev. Lett. 21, 1569 (1968).
20. T. Kanata, M. Matsunaga, H. Takakura, and Y. Hamakawa, J. Appl. Phys. 69, 3691 (1991).
21. T. M. Hsu, J. W. Sung, W. C. Lee, J. Appl. Phys., 82, 2603 (1997).
22. C. H. Goo, W. S. Lau, T. C. Chong, and L. S. Tan, Appl. Phys. Lett. 69, 2543 (1996).