摘要
　　本論文中，我們使用有機金屬化學汽相沈積來成長氮化鎵系列光檢測器之元件，並對其特性作探討。
　　首先，利用爐管在氧氣下回火鎳/金 ( 3/6 nm )半透明金屬薄膜電極，我們發現在波長320 nm下其穿透率可以由45%提昇至52%。進一步地，將鎳/金薄膜應用在製作氮化鋁鎵金屬-半導體-金屬結構之紫外光光檢測器之製作上。從實驗結果得知，由於漏電流的有效降低可導致元件於光電特性上得到一不錯的改善。之後，本論文中也製作了氮化鋁鎵金屬-絕緣層-半導體結構之紫外光光檢測器。所使用之二氧化矽絕緣層採用電漿增強式化學汽相沈積來沈積於元件之上。我們發現經由導入一層二氧化矽絕緣層，元件之特性能被有效改善。在5伏偏壓下，氮化鋁鎵金屬-絕緣層-半導體結構之紫外光光檢測器的光暗電流比可達1.47 × 103。我們也發現，氮化鋁鎵金屬-絕緣層-半導體結構之紫外光光檢測器之拒斥比更可高達1.94 × 103。
　　本實驗中，在低溫下成長不同材料覆蓋層之氮化鋁鎵金屬-半導體-金屬之紫外光光檢測器亦被製作來改良元件特性。藉由成長低溫覆蓋層，元件的漏電流可被有效減少。藉由成長低溫覆蓋層，元件的蕭基能障高度可由原來的0.718增加至0.992 ( 低溫氮化鎵覆蓋層 )及0.998 ( 低溫氮化鋁鎵覆蓋層 )電子伏特。在三種結構當中，使用氮化鋁鎵覆蓋層之氮化鋁鎵金半金結構光檢測器可得到最大的光暗電流比，約為1.94 × 104。另外，我們也觀測到元件的平緩響應特性。之後，部份蝕刻於覆蓋低溫成長氮化鋁鎵之氮化鋁鎵金半金結構光檢測器亦被製作來改善元件的平緩響應特性以及元件的低量子效應。造成這兩種現象之原因則是在於低溫成長覆蓋層會對元件之截止波長外亦有額外的吸收作用所致。
　　最後，p-氮化鎵/i-氮化銦鎵/n-氮化鎵結構之光檢測器亦在本論文中製作出來。將鎳催化之方式應用在p-氮化鎵層上可以增進元件的歐姆特性。進一步地利用氮化矽披附於元件上以降低因電感耦合電漿乾蝕刻所導致之元件表面的損傷。進而對元件之光電特性作一量測。

Abstract
　　In this thesis, the properties and characteristics investigation of Nitride-based photodetectors which had been grown by metal organic chemical vapor deposition were demonstrated.
　　First, the semi-transparent metal contact, Ni/Au ( 3/6 nm ), was annealed by furnace in oxygen. We observed that the transmittance spectra of the Ni/Au thin film can be improved from 45 % to 52 % at 320 nm. Further, we applied the Ni/Au thin film to fabricate AlGaN metal-semiconductor-metal ( MSM ) ultraviolet ( UV ) photodetectors. From the experiment results, the electrical and optical characteristic for our devices have been improved due to the reduction of the leakage current. Then, AlGaN metal-insulator-semiconductor ( MIS ) UV photodetecors were also fabricated in thesis. The SiO2 insulator was deposited by means of plasma enhanced chemical vapor deposition ( PECVD ). It was found that the devices performance have been improved by inserting the SiO2 layer. With a 5 V bias voltage, the photo-to-dark contrast ratio was 1.47 × 103 for the AlGaN MIS photodetectors. It was also found that the rejections are 1.94 × 103 for AlGaN MIS photodetecor.
　　The AlGaN MSM photodetectors with different low temperature ( LT ) grown cap layer were fabricated to improve the performance. By growing the LT cap layer, the leakage current in AlGaN MSM photodetectors can be effectively eliminated. The Schottky barrier height of AlGaN are 0.718, 0.992 and 0.998 eV for as deposited, LT-GaN and LT-AlGaN devices, respectively. Among these three devices, AlGaN MSM photodetectors with LT-AlGaN cap layer have the largest photo-to-dark contrast ratio around 1.94 × 104. Besides, the flat responsivity characteristic was also be investigated. Following, the recessed AlGaN MSM photodetectors with LT-AlGaN cap layer were fabricated to improve the flat responsivity and the low quantum efficiency originated from the additional absorption by the cap layer.
　　Finally, the p-i-n structure photodetectors with p-GaN layer, n-GaN layer and i-InGaN active layer were fabricated. The Ni catalysts technology was applied in p-GaN layer to enhance ohmic characteristics of p-type layer. Further, a SiN passivation layer was introduced in devices to reduce the leakage current originated from the ICP dry etching damage. Then, the related electrical and optical characteristics will be also measured.

Chapter 1
[ 1 ] S. Nakamura et al., “The Blue Laser Diode : GaN Based Light Emitters and Lasers”
[ 2 ] E. Monroy et al., “Wide-band gap semiconductor ultraviolet photodetectors”, Semicond. Sci. Technol., Vol 18, R33-R51 ( 2003 )
[ 3 ] E. Monroy et al., “Application and performance of GaN Based UV Detectors”, phys. stat. sol. ( a ), Vol 185, 91-97 ( 2001 )
[ 4 ] M. Razeghi et al., “Semiconductor ultraviolet detectors”, J. Appl. Phys., Vol 79, 7433-7473 ( 1996 )
[ 5 ] E. Monroy et al., “AlGaN-based UV photodetectors”, Journal of Crystal Growth, Vol 230, 537-543 ( 2001 )
[ 6 ] S. J. Pearton et al., “GaN: Processing, defects, and devices” , J. Appl. Phys., Vol 86, 1-78 ( 1999 )

Chapter 2
[ 1 ] Rolf E. Hummel et al., “Electronic Properties of Materials”, Second Edition
[ 2 ] Dieter K. Schroder et al., “Semiconductor material and device characterization”
[ 3 ] Pallab Bhattacharya et al., “Semiconductor Optoelectronic Devices”, Second Edition
[ 4 ] S. Nakamura et al., “The Blue Laser Diode : GaN Based Light Emitters and Lasers”
[ 5 ] M. Razeghi et al., “Semiconductor ultraviolet detectors”, J. Appl. Phys., Vol 79, 7433-7473 ( 1996 )
[ 6 ] E. Monroy et al., “Wide-band gap semiconductor ultraviolet photodetectors”, Semicond. Sci. Technol., Vol 18, R33-R51 ( 2003 )
[ 7 ] Y. K. Su, S. J. Chang, C. H. Chen et al., “GaN Metal – Semiconductor - Metal Ultraviolet Sensors Contact Electrodes”, IEEE SENSORS JOURNAL, Vol 2, 366-371 ( 2002 )

Chapter 3

chpter 3-1
[ 1 ] Y. K. Su, P. C. Chang. et al., “Nitride-based MSM UV photodetectors with photo-chemical annealing Schottky contacts”, Solid-State Electronics, Vol 49, 459-463 ( 2005 )
[ 2 ] Y. D. Jhou et al., “GaN MSM photodetectors with photo-CVD annealed Ni/Au electrodes”, Microelectronics Journal, Vol 37, 328-331 ( 2006 )
[ 3 ] P. C. Chang. et al., “AlGaN/GaN MSM photodetectors with photo-CVD annealed Ni/Au semi-transparent contacts”, Semicond. Sci. Technol., Vol 19, 1354-1357 ( 2004 )
[ 4 ] J. K. Ho et al., “Low-resistance Ohmic contacts to p-type GaN achieved by the oxidation of Ni/Au films”, J. Appl. Phys., Vol 86, 4491-4497 ( 1999 )
[ 5 ] H. W. Jang et al., “Mechanism for Ohmic contact formation of oxidized NiÕAu on p-type GaN ”, J. Appl. Phys., Vol 94, 1748-1752 ( 2003 )
[ 6 ] L. C. Chen et al., “Microstructural investigation of oxidized Ni/Au Ohmic contact to p-type GaN” , J. Appl. Phys., Vol 86, 3826-3832 ( 1999 )

chapter 3-2
[ 1 ] P. C. Chang. et al., “InGaN/GaN Multi-Quantum Well Metal-Insulator Semiconductor Photodetectors with Photo-CVD SiO2 Layers”, Jpn. J. Appl. Phys., Vol 43, 2008-2010 ( 2004 )
[ 2 ] P. C. Chang. et al., “High UV/visible rejection contrast AlGaN/GaN MIS photodetectors”, Thin Solid Films, Vol 498, 133-136 ( 2006 )
[ 3 ] J. D. Hwang. et al., “Nitride-Based UV Metal – Insulator– Semiconductor Photodetector with Liquid-Phase-Deposition Oxide”, Jpn. J. Appl. Phys., Vol 44, 7913-7915 ( 2005 )
[ 4 ] M. Setoo et al., “Low-leakage-current metal – insulator – semiconductor – insulator – metal photodetector on silicon with a SiO2 barrier-enhancement layer”, Appl. Phys. Lett., Vol 75, 1976-1978 ( 1999 )
[ 5 ] M. Munoz et al., “III nitrides and UV detection ”, J. Phys.: Condens. Matter, Vol 13, 7115-7137 ( 2001 )
[ 6 ] E. Monroy et al., “Low-noise metal-insulator-semiconductor UV photodiodes based on GaN” , ELECTRONICS LETTERS, Vol 25, 2096-2098 ( 2000 )

Chapter 4

chapter 4-1
[ 1 ] S. J. Chang., M. L. Lee et al., “GaN Metal –Semiconductor-Metal Photodetectors With Low-Temperature-GaN Cap Layers and ITO Metal Contacts”, IEEE ELECTRON DEVICE LETTERS, Vol 24, 212-214 ( 2003 )
[ 2 ] P. C. Chang. et al., “Reduction of Dark Current in AlGaN-GaN Schottky-Barrier Photodetectors With a Low – Temperature - Grown GaN Cap Layer”, IEEE ELECTRON DEVICE LETTERS, Vol 25, 593-593 ( 2004 )
[ 3 ] T. K. Ko et al., “AlGaN-GaN Schottky-barrier photodetectors with LT GaN cap layers”, Journal of Crystal Growth, Vol 283, 68-71 (2005)
[ 4 ] M. L. Lee et al., “GaN Schottky barrier photodetectors with a low-temperature GaN cap layer”, Appl. Phys. Lett., Vol 82, 2913-2915 ( 2003 )
[ 5 ] J. K. Sheu et al., “Effect of low-temperature-grown GaN cap layer on reduced leakage current of GaN Schottky diodes”, Appl. Phys. Lett., Vol 86, 052103-1 - 052103-3 ( 2005 )
[ 6 ] M. Mikulics et al., “Ultrafast metal – semiconductor - metal photodetectors on low-temperature-grown GaN” , Appl. Phys. Lett., Vol 86, 211110-1 - 211110-3 ( 2005 )
[ 7 ] M. L. Lee et al., “Schottky barrier heights of metal contacts to n-type gallium nitride with low – temperature - grown cap layer”, Appl. Phys. Lett., Vol 88, 032103-1 - 032103-3 ( 2006 )
[ 8 ] C. J. Kao et al., “Comparison of low-temperature GaN, SiO2, and SiNx as gate insulators on AlGaN/GaN heterostructure field-effect transistors”, J. Appl. Phys., Vol 98, 064506-1 - 064506-3 ( 2005 )
[ 9 ] T. K. Ko et al., “AlGaN-GaN Schottky-barrier photodetectors with LT GaN cap layers”, Journal of Crystal Growth, Vol 283, 68-71 (2005)

chapter 4-2
[ 1 ] N. Biyikli et al., “Solar-Blind AlGaN-Based p-i-n Photodiodes With Low Dark Current and High Detectivity”, IEEE PHOTONICS TECHNOLOGY LETTERS, Vol 16, 1718-1720 ( 2004 )
[ 2 ] C. L. Yu et al., “In0.37Ga0.63N Metal – Semiconductor – Metal Photodetectors With Recessed Electrodes”, IEEE PHOTONICS TECHNOLOGY LETTERS, Vol 17, 875-877 ( 2005 )
[ 3 ] H. Jiang et al., “GaN Metal-Semiconductor-Metal UV Photodetector with Recessed Electrodes”, Jpn. J. Appl. Phys., Vol 41, L 34-L 36 (2002)
[ 4 ] S. J. Chang., M. L. Lee et al., “GaN Metal – Semiconductor – Metal Photodetectors With Low-Temperature-GaN Cap Layers and ITO Metal Contacts”, IEEE ELECTRON DEVICE LETTERS, Vol 24, 212-214 ( 2003 )
[ 5 ] T. K. Ko et al., “AlGaN-GaN Schottky-barrier photodetectors with LT GaN cap layers”, Journal of Crystal Growth, Vol 283, 68-71 (2005)
[ 6 ] M. L. Lee et al., “GaN Schottky barrier photodetectors with a low-temperature GaN cap layer”, Appl. Phys. Lett., Vol 82, 2913-2915 ( 2003 )
[ 7 ] P. C. Chang. et al., “Reduction of Dark Current in AlGaN–GaN Schottky-Barrier Photodetectors With a Low – Temperature - Grown GaN Cap Layer”, IEEE ELECTRON DEVICE LETTERS, Vol 25, 593-593 ( 2004 )

[ 8 ] J. K. Sheu et al., “Effect of low-temperature-grown GaN cap layer on reduced leakage current of GaN Schottky diodes”, Appl. Phys. Lett., Vol 86, 052103-1 - 052103-3 ( 2005 )
[ 9 ] M. Mikulics et al., “Ultrafast metal – semiconductor - metal photodetectors on low-temperature-grown GaN” , Appl. Phys. Lett., Vol 86, 211110-1 - 211110-3 ( 2005 )
[ 10 ] C. J. Kao et al., “Comparison of low-temperature GaN, SiO2, and SiNx as gate insulators on AlGaN/GaN heterostructure field-effect transistors”, J. Appl. Phys., Vol 98, 064506-1 - 064506-3 ( 2005 )
[ 11 ] M. L. Lee et al., “Schottky barrier heights of metal contacts to n-type gallium nitride with low – temperature - grown cap layer”, Appl. Phys. Lett., Vol 88, 032103-1 - 032103-3 ( 2006 )
[ 12 ] T. K. Ko et al., “AlGaN-GaN Schottky-barrier photodetectors with LT GaN cap layers”, Journal of Crystal Growth, Vol 283, 68-71 (2005)

Chapter 5
[ 1 ] S. Nakamura et al., “P-GaN / N-InGaN / N-GaN Double-Heterojunction Blue-Light-Emitting Diodes”, Jpn. J. Appl. Phys. 32, L 8–L 11 ( 1993 )
[ 2 ] Y. Z. Chiou et al., “InGaN/GaN MQW p-n junction photodetectors”, Solid-State Electronics, 46, 2227-2229 ( 2002 )
[ 3 ] L. W. Ji et al., “InGaN quantum dot photodetectors”, Solid-State Electronics, 47, 1753-1756 ( 2003 )
[ 4 ] S. Nakamura et al., “The Blue Laser Diode : GaN Based Light Emitters and Lasers”
[ 5 ] I. Waki et al., “Mechanism for low temperature activation of Mg-doped GaN with Ni catalysts”, J. Appl. Phys. 90, 6500 – 6504 ( 2001 )
[ 6 ] S. M. Wang et al., “Mg-doped GaN activated with Ni catalysts”, Materials Science and Engineering B, 117, 107-111 ( 2005 )