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本論文提出下列四種新的非晶質光偵測器元件的構造、製作與特性：
(1)非晶矽穿透累崩光二極體。
(2)非晶矽／碳化矽穿透累崩光二極體。
(3)非晶矽／碳化矽異質接面光電晶體。
(4)辨別色光的非晶矽光電晶體。
在5 微瓦氦氖雷射入射光功率及14.5伏特的反向偏壓下，電子入射式非晶矽穿透累崩
光二極體光增益可達380 。在倍乘值為33.46 時，其過雜訊因子為6.47。在1.8 仟歐
姆的負載電阻下，其動態交換上升時間為1 微秒。電洞與電子撞擊游離率（β與α）
，在電場Ｅ由５＊１０5 至３．５＊１０6 伏特／厘米的範圍內，可闊別表示成β
(E)=9.87*10(四次方)EXP(-1.36*10(六次方)/E)每厘米及α(E)=6.34*10(五次方)
exp(-3.16 * 10(五次方)/E) 每厘米。由本研究的結果，可知非晶矽穿透累崩光
二極體可以作為光感測器。
典型的電子入射式非晶矽／碳化矽超晶格穿透累崩光二極體，由於累崩區中有超晶格
可改良特性，當電場為3.33*10(六次方) 伏特／厘米時，其電子與電洞撞擊游離率的
比值（α／β）可達10.2，此比值是利用光電沆倍乘測量法獲得，而且也利用過雜訊
因子測量法檢查是否正確。在5 微瓦氦氖雷射入射光功率及18伏特的反向偏壓下，其
光增益高達506 。在負載電阻為1 仟歐姆時，其上升時間為1 微秒。在倍乘值為48時
，過雜訊因子為6.53。這些結果均比從前提出的非晶質光偵測器的性能更好。
為改良同質接面非晶矽光電晶體的特性，本論文提出另一種非晶矽／碳化矽異質接面
光電晶體。其結構為玻璃/ ITO/非晶矽(n+-i-δp)+/非晶碳化矽(i-n+)/ 鋁，其中薄
的δp+非晶矽層能隙較窄，當作基極用，而與非晶碳化矽射極形成異質接面。此異質
接面元件的最佳光增益為40，反應速度為10微秒，比以前提出的同質接面元件的性質
改善很多。此種特性改善的原因也加以說明。
最後提出一種能辨別色光的非晶矽光電晶體，其結構為鋁／
n+-i-p+-i-n-i-p-i-n+/ITD玻璃。其頻譜響應的最小的。在可見光範圍內，其頻譜響
應峰值波長在4000埃至5400埃的範圍可利用所加的偏壓調整。元件的電流─電壓特性
與理論上的考慮大致符合。其最高光增益值是10。
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In this thesis, the structures, fabrications and characteristics of four
novel amorphous photodetectors, i.e. a-Si; H reach-through avalanche
photodiode (RAPD), a-Si:H/Sic::H superlattice RAPD (SRAPD), a-Si:H/SiC:H
heterojunction phototransistor (HPT), and color-sensitive a-Si:H
phototransistor (PT) are presented.
For the electron-injection A-Si:H RAPD, an optical gain of 380 can be
obtained under 5 μW He-Ne laser input light power and at a reverse-bias
voltage of 14.5V. The excess noise factor is 6.47 at a multiplication of
33.46. The dynamic rise time of 1μs 0has been observed under a 1.8 kΩ
load resistance. The hole and electron impact ionization rates (β and α)
can be expressed empirically by β (E)=9.87*104EXP(-1.36*106/E)cm-1 and α
(E)=6.34*105*exp(-3.16*105/E)cm-1 for electric field E ranging from 5-105
to 3.5*106V/cm respectively. Based on the results of this study, the
a-Si:H rapd would be a promising a-Si:H device for the photosensing
application.
As for a typical electron-injection a-Si:H/SiCH SRAPD, due to the
performance enhancement by superlattice in avalanche region, the ratio of
room-temperature electron and hole impact ionization rates (α/β) is 10.2
at an electric field of 3.33*106V/cm as determined by the photocurrent
multiplication measurement and checked by the excess noise factor method,
the optical gain is 506 at an applied reverse-bias VR = 18 V and an
incident power Pin= 5μW emitted from a He-Ne laser, the rise time is 1μ
s at a load resistance RL=1kΩ, and the excess noise factor is 6.53 at a
ultiplication M=48. These results are better than those of the other
amorphous photodetectors ever reported.
In order to improve the performance of the a-Si:H homojunction
phototransistor, an alternative a-Si:H/SiC:H heterojunction
phototransistor is proposed. The structure is glass/ITC/a-Si:H (n+-iδ
p+)/a-SiC:H(i-n+)/Al, in which the thin δp+ a-Si:H layer of smaller
band-gap is embedded as the base which forms the heterojunction with the
a-Si:H emitter. This heterojuction device reveals a significant
improvement over the previously reported homojunction ones, with an
optimal optical gain of 40 and a response time of 10μs. The physical
phenomenon which causes this performance improvement is described
qualitatively also.
Finally, a color-sensitive a-Si:H phototransistor with the structure of
Al/n+-i-p+-i-n-i-o-i-n+/ITO/glass has been fabricated successfully. Its
spectral response reveals a minimum FWHM (Full Width Half Maximum) of 600
A° which is the smallest width ever reported for amorphous
phototransistors. The peak spectral response in visible range can be
shifted from 4000 A°to 5400 A°by applied bias. The experimental I-V
characteristics is fitted by the theoretical consideration qualitatively.
A maximum optical gain of 10 is obtainable.
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