本文係利用電調制反射光譜(Electroreflectance spectrum)來量測及分析具有蕭基位障的氮化鎵(Au/n-GaN)在不同偏壓下光譜的變化，我們發現當光能量(Photon energy)在小於 GaN 能隙(Energy gap)時會光譜會有激子(Exciton)的訊號產生；此外當光能量(Photon energy) 在高於能隙(Energy gap)能量，光譜則會有Franz-Keldysh oscillations(FKOs)訊號的產生。當我們所加偏壓( )=0 時，此二訊號(Exciton and FKOs signal)是混合的，但當我們慢慢增加負偏壓(reverse )時，這兩個訊號則會慢慢分離，再此實驗中我們觀測到Exciton 訊號有紅位移而FKOs 訊號則有藍位移現象。
我們可以藉由FKOs的振盪週期來計算GaN的表面電場強度( )。利用 VS 作圖，金屬位障 (barrier height)1.2V及載子濃度 (carrier concentration ) 則可決定之。

Electroreflectance (ER) spectra of Schottky-barrier Au/n-GaN have been measured at various dc biased voltages (Vbias). The ER spectra have exhibited excitonic signals beneath band-gap energy (Eg ). In addition, Franz-Keldysh oscillations (FKOs) were also observed above Eg. The FKOs come from the former region, and the excitonic signals come from the latter region. When Vbias = 0, they are mixed. As reverse Vbias is increased, they become more separated. Furthermore, strength of surface electric field (Fs) can be deduced from the period of the FKOs. From the plot of versus Vbias, barrier height of 1.2 V and carrier concentration were obtained.

第一章 簡介………………………………………………………1
第二章 調製光譜原理
2.1 調製光譜學的機制………………………………………6
2.2 介電函數與反射率………………………………………10
2.3 譜線圖形分析……………………………………………13
2.4 Franz-Keldysh Oscillations 與
asymptotic form…………………………………………19
第三章 實驗設計與操作
3.1 實驗樣品與能帶結構……………………………………23
3.2 氮化鎵半導體裡常見的光學躍遷………………………33
3.3 實驗裝置…………………………………………………36
第四章 實驗結果與討論…………………………………………38
第五章 結論………………………………………………………45

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