鍺量子點光電晶體暫態載子傳輸特性分析

Characterization of carrier dynamics in Ge quantum dots through Ge quantum-dot MOSFETs using pulsed voltage technique

陳和謙(Ho-Chien Chen)

指導教授 ： 李佩雯 ； 郭明庭

國立中央大學/資訊電機學院/電機工程學系/碩士(2015年)

摘要

鍺材料具有高載子遷移率及窄能隙等優點，搭配此材料製作的半導體元件，得以實現適用於波長1.55μm之光偵測器或是高速電晶體。
　　本論文針對鍺量子點金氧半與單電洞電晶體，開發合適的高速脈波量測系統。由控制程式的設計，佐以高靈敏度的硬體配置，進行瞬時同步的脈波輸入和電氣訊號輸出。利用此量測系統，可透過改變脈波輸入時間、輸入電壓或脈波輸入元件端，觀察在不同輸入條件下，鍺量子點元件中瞬間開關/切換的暫態響應，進而了解鍺量子點元件的即時操作行為以及推論載子在鍺量子點元件內部的時變傳輸機制。
　　量測結果顯示，鍺量子點光電晶體受到高速的閘極脈衝驅動後，會迅速進入深度空乏暫態，產生暫態過衝電流等與穩態截然不同的電流特性。且當脈衝電壓、溫度、閘介電層厚度、以及光照強度等條件發生改變時，元件在非平衡態下的瞬間少數載子數量有顯著變化，可明顯由鍺量子點光電晶體之暫態響應觀察到。反觀鍺量子點單電晶體或者無量子點的金氧半場效電晶體，皆未觀察到如光電晶體般奇特的暫態反應。
　　深入探討上述的鍺量子點元件的載子傳輸機制，有助於相關元件的改良、設計，甚至利用其時變操作特性，進一步開發適合應用的上市電子產品。

關鍵字

光電晶體 ； 鍺量子點 ； 暫態

並列摘要

In this thesis, we designed a high-speed pulse system for Ge QD MOS phototransistors and single hole transistors(SHT). With this measurement system, synchronization on voltage pulse input and current signal output measurement can be implemented. Consequently, dynamic current change happened in Ge QD electronic devices is studied in different input conditions such as pulse width and pulse voltage. Furthermore, the carrier dynamic transport mechanism is investigated.
Ge QD MOS phototransistors driven by high-speed gate voltage pulses would quickly go into transient deep depletion state, which shows an electrical behavior different from the thermal equilibrium states such as overshoot current. The quantity of transient non-equilibrium minor carriers in Ge QD MOS phototransistors have tremendous differences with various illumination power, pulse voltage, temperature and gate oxide thickness. Such transient response is only observable in Ge QD MOS phototransistors but not in MOSFETs without Ge QD and Ge QD single hole transistors.
Further studies on transient transportation of the Ge QD MOS phototransistors can provide helpful information for improvement and applications in the future.

參考文獻

[1] H. J. R. Dutton, “Understanding Optical Communications,” p4, 1998.

[2] J. N. Shive, “A new germanium photo-resistance cell,” Phs. Rev., 76, 575, 1949.

[3] W. Shockley, M. Sparks, and G. K. Teal, “P-n junction transistors,” Phs. Rev., 83, 151, 1951.

[4] K. Matsumoto et al., “A New MOS Phototransistor Operating in a Non-Destructive Readout Mode, ”Japanese Journal of Applied Physics, 24, no.5, L323-325, 1985.

[5] R. H. Walden, “A review of recent progress in InP-based optoelectronic integrated circuit receiver front-ends,” Int. J. High Speed Electron. Syst., 9, 631, 1998.