近紅外光單晶鍺薄膜光偵測器

本論文主旨為製作近紅外光之金屬-鍺-金屬光偵測器(metal-germanium-metal photodetector)並加以量測及分析。鍺的吸收波段恰可應用於光通訊常用之近紅外光波長850nm、1310nm與1550nm，但因為鍺本身價格昂貴，故本實驗先利用濺渡方式在矽基板上長出單晶鍺薄膜後再製作光偵測器，藉由此方式不僅可以保留鍺在近紅外光出色的表現也可以大大降低生產成本。　　本研究使用指叉狀電極(Interdigitated electrode)做為光偵測器之電極，其目的是利用簡單的製程做出高頻的元件並希望可將其應用於IC設計當中。本實驗主要使用三種不同基板製作光偵測器，分別是矽基板、鍺基板與鍍在矽基板上的鍺薄膜，除了響應度(responsivity)及頻率響應(frequency response)的量測與分析外，還會分析膜品質對於元件的影響。本實驗矽基板之光偵測器響應度最高可達0.46A/W，頻率響應可達43.35MHz，而鍺基板跟鍺薄膜的響應度則分別為0.257A/W及2.71mA/W。

關鍵字

光偵測器；鍺薄膜；濺鍍；鈍化；金屬-半導體-金屬；蕭特基接觸

並列摘要

The particular metal-germanium-metal photodetector (PD) is investigated in this research. Germanium has good absorption coefficient in near infrared such as 850nm, 1310nm and 1550nm which are commonly used in optics communication. Unfortunately, the prohibitive cost of germanium wafer makes it difficult to popularize. Radio frequency (RF) sputtering system is used to deposit single crystal intrinsic germanium film to fabricate the photodetector. It not only keeps performance of Ge but also reduces the cost more than a factor of five. In this investigation, interdigitated electrodes are used on the devices with the purposes of a relative easy process for high-speed devices and a comparable process for the integrated circuit. Three different substrates are used to fabricate photodetectors including n-Si, p-Ge and i-Ge/n-Si. Responsivities and frequency responses are measured and analyzed. Besides, the effect of the Ge thin film on the device was also discussed. The responsivity of PDs are 0.46A/W, 0.257A/W and 2.71mA/W for n-Si, p-Ge and i-Ge/n-Si respectively. The frequency response can be achieved 43.35MHz for Si-based MSM PD.

並列關鍵字

photodetector ； germanium thin film ； suputtering ； passivation ； metal-semiconductor-metal ； schottky

參考文獻

1. H.C. Luan, D.R. Lim, K.K. Lee, K.M. Chen, J.G. Sandland, K. Wada and L.C. Kimerling, High-quality Ge epilayers on Si with low threading-dislocation densities. Applied Physics Letters, 1999. 75(19): p. 2909-2911.

2. Y. Fukuda and Y. Kohama, High quality heteroepitaxial Ge growth on (100) Si by MBE. Journal of Crystal Growth, 1987. 81(1–4): p. 451-457.

3. M.T. Currie, S.B. Samavedam, T.A. Langdo, C.W. Leitz and E.A. Fitzgerald, Controlling threading dislocation densities in Ge on Si using graded SiGe layers and chemical-mechanical polishing. Applied Physics Letters, 1998. 72(14): p. 1718-1720.

4. D. Choi, Y. Ge, J.S. Harris, J. Cagnon and S. Stemmer, Low surface roughness and threading dislocation density Ge growth on Si. Journal of Crystal Growth, 2008. 310(18): p. 4273-4279.

5. V.A. Shah, A. Dobbie, M. Myronov and D.R. Leadley, Effect of layer thickness on structural quality of Ge epilayers grown directly on Si(001). Thin Solid Films, 2011. 519(22): p. 7911-7917.

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近紅外光單晶鍺薄膜光偵測器

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