以原子層化學氣相沉積法製作氮化鈦/二氧化鈦薄膜光感測器之探討

Investigation of Titanium Nitride/Titanium Dioxide Thin-Film Photodetector Fabricated by Atomic Layer Chemical Vapor Deposition

陳紀軒(Chi-Hsuan Chen)

指導教授 ： 楊斯博

國立交通大學/光電學院/照明與能源光電研究所/碩士(2018年)

摘要

一般來說半導體若要產生由光激發的載子，首先必須對於入射光有足夠的吸收，而光的吸收決定於材料的能隙大小，對於高能隙半導體材料二氧化鈦(Titanium Dioxide, TiO2)而言，可見光、紅外光能量較低不足以越過能隙而無法被加以利用；因此，在我們的研究中，使用原子層化學氣相沉積系統(Atomic Layer Chemical Vapor Deposition, ALCVD)在不同製程條件的二氧化鈦表面沉積氮化鈦(Titanium Nitride, TiN)薄膜作為光吸收金屬層，底層採用氧化銦錫(Indium Tin Oxide, ITO)作為電子導出層以利電子傳輸；透過多項量測分析確認能夠於紫外光至紅外光波段激發TiN電子越過TiO2界面並測得相當顯著的光響應，不過傳輸的特性上很大程度受到TiO2能隙內的缺陷能階所影響，包括較大的暗電流、光響應的延遲現象…等，其光電子的激發及傳輸特性相當特殊，若要作為光感測器尚須找到更佳的製程條件以減少缺陷能階之效應。

關鍵字

氮化鈦 ； 二氧化鈦 ； 原子層沉積 ； 光感測器

並列摘要

Typically, to generate photo-excited carriers from a semiconductor, enough absorption for the incident photons is necessary. In principle, the optical absorption is determined by the band gap of the material. As long as the energy of the incoming photons is larger than the band gap, it will be absorbed. This leads to the fact that it can convert the light energy into electrical energy. For a wide-band-gap material like titanium dioxide (TiO2), the energy of both visible and infrared light are obviously too low to overcome the band gap of it. Therefore, in this research we use Atomic Layer Chemical Vapor Deposition System to deposit a titanium nitride (TiN) thin film on top of the TiO2 film as the light absorption layer which can help overcome the limitation of the band gap. Also, indium tin oxide (ITO) is used as the electron transport layer in this case. Through multiple measurements and analyses, it is found that there is a significant photo-response of TiN from ultraviolet to infrared region. However, the electron transport characteristics are greatly affected by the defect levels in the band gap of TiO2, such as large dark current and delayed response. The mechanism of photoelectron excitation and transmission are quite special. If it is to be served as a photodetector, better process conditions must be found to reduce the effect of defect level.

並列關鍵字

Titanium Nitride ； Titanium Dioxide ； Atomic Layer Deposition ； Photodetector

參考文獻

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