金氧半光偵測器

Novel Metal-Insulator-Semiconductor Photodetectors

郭平昇(Ping-Sheng Kuo)

指導教授 ： 劉致為

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.00856

摘要

本論文中，我們利用金氧半穿隧二極體中閘極電流有光反應的特性來製作光偵測器。由於鍺融點的關係我們以液相沈積法代替傳統的熱成長法來成長氧化層, 且由於液相沈積法成長的氧化層有較多的缺陷所以有較高的效率, 我們嚐試在液相沈積法中加入氨水發現氮原子可降低氧化層中的缺陷, 而擁有較低的正負偏壓的電流, 進而提高其長波長操作溫度. 我們將之成長在鍺量子點上形成嵌壁式氮氧量子點, 與沒有氮原子的二氧化矽量子點相比擁有較高的高度.
為了增加金氧半光偵測器的截止波長及效率，我們利用鍺及鍺量子點來作為光吸收層。利用液相沈積來成長氧化層可避免高溫製程對矽鍺結構造成損害。而此鍺光偵測器可操作於1.3及1.5微米之下並可應用於光纖通訊。其量子效應達到50 %且響應在1.5微米可達0.5 A/W。而利用五層鍺量子點結構之元件亦可操作於820、1300、1550奈米波段，其對應響應為130、0.16、0.08 mA/W。若利用二十層的鍺量子點作為吸收層，在850奈米之響應更高達600 mA/W。
我們提出金氧半光偵測器亦可用於中長波長之紅外光偵測上。利用電洞在價帶間的躍遷，吸收波長可達10微米。利用氮氧化層作為閘極絕緣層，元件最高操作溫度在2 ~ 3微米可達200 K，在3 ~ 10微米亦可達140 K。
我們也試著用不同的金屬來代替鋁當電極, 由於鉑金屬擁有較大的巨蝻

關鍵字

光偵測器 ； 量子點 ； 鍺 ； 鉑

並列摘要

In this thesis, the metal-oxide-semiconductor (MOS) tunneling diodes were utilized as photodetectors based on that the gate current has a photo-response. We use liquid phase deposition (LPD) method instead of traditional thermal method to deposit oxide films, and the LPD has a higher efficiency due to more defects in it. By adding NH4OH into LPD solution, we find the N atoms can reduce defects in oxynitride and the film with fewer defects has a lower current and higher operation temperature in long wavelength range (2~10 μm). Recessed oxynitride dots are demonstrated by depositing LPD oxynitride on Ge quantum dots substrate and they have a higher dot height than oxide dots.
To increase the cutoff wavelength and efficiency of the MOS detector, Ge and Ge/Si quantum dots are used as absorption layers. The oxide is directly grown on Ge substrate by liquid phase deposition to reduce thermal budget. This Ge photodetector can operate at 1.3 and 1.5 μm lightwave and can be applied to the fiber-optic communications. The maximum external quantum efficiency is estimated approximately 50 %, and responsivity can reach 0.5 A/W at 1.5 μm. The five-period Ge quantum dot MOS device can detect the wavelengths of 820 nm, 1300 nm, and 1550 nm with the responsivity of 130, 0.16, and 0.08 mA/W, respectively. The responsivity at 850 nm reaches 600 mA/W using a 20-period Ge quantum dot absorption layer.
Finally, the MOS Ge/Si quantum dot infrared photodetectors (QDIPs) for 2 ~ 10 μm using hole inter-valance subband transitions are demonstrated. The maximum operating temperature is 140 K for 3 ~ 10 μm and is up to 200 K for 2 ~ 3 μm detection with LPD oxynitride.
We also attempt to use different metal instead of aluminum to form the electrode. Because of the platinum has a higher workfunction, the current transition mechanism is different. For Ge quantum dots devices with platinum gate, the current has photo-response under both positive and negative bias. So the dual-polarity operable MOS photodetector is demonstrated. In addition, we also study the hole blocking effect which can effectively lower the hole current. With the lower temperature, the holes confined in the dots can obtain less energy to jump out of the dots.

並列關鍵字

photodetector ； Ge ； Pt ； quantum dot

參考文獻

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