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P-Type GaN Schottky Diodes Study
GaN;Ohmic contact;Specific contact resistance;Surface Fermi level
|Issue Date: ||2013-10-02T08:37:48Z
(A) p 型氮化鎵有效活化方式之開發與其對表面費米能階和產生自由載子濃度的特性分析，建立p 型氮化鎵活化之機制將p 型氮化鎵經過不同形式之活化後經霍爾(Hall)觀測系統測量p 型氮化鎵載子濃度，並以x 光光電子能譜(XPS)術和深紫外光光電能譜(UPS)術觀測經活化的試片表面，整合分析p 型氮化鎵的表面能帶分布情形。
(B) 金屬/p 型氮化鎵歐姆接觸特性分析選擇合適之金屬蒸鍍在經有效活化後之p 型氮化鎵上，以電流-電壓(I-V)法測量其特徵接觸電阻，並以XPS 剖面分析技術深入研究熱處理前後金屬/p 型氮化鎵界面之特性。為了建立完善之歐姆接觸機制，也將製作金屬/p型氮化鎵蕭特基二極體，以I-V 和電容-電壓(C-V)法觀測界面之特性。
GaN has a 3.4 eV direct gap at room temperature and has attached much interest for its application in optical devices in the short-wavelength region such as blue light emitting diodes (LEDs) and laser diodes (LDs). Other devices that have been demonstrated so far include ultraviolet photoconductive detectors, ultraviolet Schottky barrier photodetectors, metal – semiconductor field effect transistors, and high electron mobility transistors. Ohmic contacts to p-GaN with low resistance are essential in improving the performances of optical devices. In order to improve the ohmic performance of the metals/p-GaN samples, the samples were annealed at the higher temperature. High-temperature annealing led to the formation of defects, which resulted in degrading the performance of optical devices, in the p-GaN sample. So in this plan, we are devoted to improve the nonalloyed and alloyed ohmic contact of p-GaN samples under the various activations. Using the Van der Pauw-Hall easurement performed, the electron concentration of the p-GaN epilayer was determined. A specific contact resistance was measured using the transmission line method (TLM) for metals contacts to the p-GaN samples. In order to investigate the interfacial characteristics for the metal/p-GaN, all samples were measured using current-voltage (I-V) method, capacitance-voltage (C-V) measurement, x-ray photoelectron spectroscopy (XPS), and ultraviolet photoelectron spectroscopy (UPS).
(A) Study the activation of p-GaN under the various conditions:
In this work, the position of surface Fermi level of p-GaN samples under the various activations can be obtained using UPS measurement and XPS measurement. Using the Van der Pauw-Hall measurement performed, the electron concentration of the p-GaN epilayer was determined. The Ga/N atomic concentration ratio on the activated p-GaN samples was measured by XPS. In order to understand the activation mechanisms of p-GaN samples under the various activations, all observed results from Hall, XPS, and UPS were further analyzed.
(B) Study the characteristics of metals nonalloyed and alloyed ohmic contacts to p-GaN samples The characteristics of Pt, Ni and Au (nonalloyed and alloyed) ohmic contacts to the activated p-GaN are measured using I-V in this work. The interfacial characteristics for metal/p-GaN are analyzed using XPS measurement. The formation mechanisms of ohmic contacts for the metals/p-GaN will be investigated in this study. In order to understand the interfacial characteristics of metal/p-GaN samples, the fabricated Schottky diodes of p-GaN were analyzed using the C-V measurements.
|Relation: ||國科會計畫, 計畫編號: NSC91-2218-E035-007; 研究期間: 9112-9207|
|Appears in Collections:||[光電科技研究所] 國科會計畫|
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