| 摘要: | 本論文研究鈦/鉑/金與磷化銦鋁鎵表面接觸之蕭特基特性，再將寬能隙的磷化銦鋁鎵覆蓋層及緩衝層加入砷化鎵金屬-半導體-金屬光檢測器結構中，研究元件特性之改善。最後利用光電化學氧化法於砷化鎵/磷化銦鋁鎵及磷化銦鋁鎵/砷化鎵/磷化銦鋁鎵金屬-半導體-金屬光檢測器之指叉狀電極間各別成長砷化鎵及磷化銦鋁鎵氧化層作為表面鈍化層，減少表面的缺陷，以提升元件特性。 於鈦/鉑/金與磷化銦鋁鎵表面接觸之蕭特基特性研究中，先利用不同化學溶液氧化物蝕刻緩衝液(BOE，Buffered Oxide Etch，係 HF與NH4F以1：6之比例混合而成的腐蝕劑)、稀釋的鹽酸和稀釋的氨水各別處理磷化銦鋁鎵表面後，研究金屬與磷化銦鋁鎵接觸之蕭特基特性。研究中發現利用稀釋的氨水處理磷化銦鋁鎵表面可獲得最佳的蕭特基特性，理想因子及蕭特基位障分別為1.10及1.08eV，並且其崩潰電壓可高達-58V。另一方面利用在稀釋氨水不同時間(10秒、30秒、60秒和90秒)各別處理磷化銦鋁鎵表面，其表面分別利用穿透式電子顯微鏡及原子力顯微鏡觀察，研究其表面變化與蕭特基特性之關係，其中以稀釋氨水處理磷化銦鋁鎵表面30秒可獲最佳的蕭特基特性。 在光檢測器方面，藉由利用寬能隙材料磷化銦鋁鎵為砷化鎵金屬-半導體-金屬光檢測器結構中的覆蓋層及緩衝層，可以有效降低元件暗電流及低頻內部增益，其暗電流於-10V偏壓下只有70pA。於此研究中，直接利用金屬-半導體-金屬光檢測器元件結構計算其理想因子及蕭特基位障。於元件的光特性方面，利用不同瓦數波長為841nm的半導體雷射照射，其光響應度為0.28A/W，另外亦量測該金屬-半導體-金屬光檢測器之光響應度與不同波長之關係。 最後，研究利用光電化學氧化法於砷化鎵/磷化銦鋁及磷化銦鋁鎵/砷化鎵/磷化銦鋁鎵金屬-半導體-金屬光檢測器之指叉狀電極間各別成長砷化鎵及磷化銦鋁鎵氧化層作為表面鈍化層，減少表面的缺陷，量測結果顯示，經氧化後之光檢測器，可以明顯降低暗電流及提升元件的崩潰電壓。 In this dissertation, we investigate the Schottky performance of the material of InAlGaP in contact with the Schottky Ti/Pt/Au metals. We use different chemical solutions to treat the InAlGaP surface to improve the Schottky diode performance. We also employ wide bandgap In0.5(Al0.66Ga0.34)0.5P (referred to as InAlGaP, hereafter), lattice-matched to GaAs, for the capping layers and buffer layer in the GaAs MSM-PDs, to improve the performance of the MSM-PDs. We also use the photoelectrochemical oxidation method to directly grow the oxide film of GaAs and InAlGaP between the interdigital electrodes of MSM-PDs for a passivation layer. This reduces surface defects and improves the performance of the passivated MSM-PDs. First, we compare the characteristics of Au/Pt/Ti/InAlGaP/GaAs Schottky diodes with different chemical solutions treated the InAlGaP surface. The chemical solution treatements include buffered oxide etchant (BOE), diluted HCl and diluted NH4OH. Among the various surface treatments mentioned, the best Schottky performances are achieved after using NH4OH+10H2O for 30sec to treat the InAlGaP surface. The ideality factor and the Schottky barrier height are 1.10 and 1.08eV, respectively, and the highest breakdown voltage is –58V. We also investigate the characteristics of Au/Pt/Ti/InAlGaP/GaAs Schottky diodes treated with NH4OH+10H2O for various times (10sec, 30sec, 60sec and 90sec). The results of TEM (transmission electron microscopy) and AFM (atomic force microscopy) measurement are also used to analyze the degradation mechanisms of Schottky diodes treated with diluted NH4OH for various times. The best Schottky performances are achieved using NH4OH+10H2O for 30sec to treat the InAlGaP surface. We employ the wide bandgap InAlGaP material for the capping and buffer layers in GaAs MSM-PD structure, to effectively reduce the dark current and avoid the low-frequency internal gain. The dark current of the InAlGaP/GaAs MSM-PDs is 70pA at –10V. In this study, we also investigate the possibility of evaluating the main Schottky contact parameters directlyfrom the InAlGaP/GaAs MSM-PD structure. The MSM-PDs are illuminated by different optical powers (semiconductor laser, wavelength of 841nm); the measured photoresponsivity is 0.28A/W. The spectral photoreponsivity is determined with a monochromator and a Xe lamp source. Finally, to improve the stability of MSM-PDs, we use a photoelectrochemical oxidation method to directly grow the oxide film of GaAs and InAlGaP between the interdigital electrodes of MSM-PDs. This acts as a passivation layer to reduce surface defects. From the experimental results, we see that the process of oxide passivated can reduce the dark current and increase the breakdown voltage of MSM-PDs. |
