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|Title: ||P型氮化硼的導電性;Electrical conductance of P-type Boron Nitride|
|Authors: ||Nguyet, Nguyen Thi Anh;Nguyet, Nguyen Thi Anh|
|Keywords: ||P型氮化硼;Electrical conductance of P-type Boron Nitride|
|Issue Date: ||2019-09-03 14:43:12 (UTC+8)|
|Abstract: ||CHINESE ABSTRACT|
深紫外線 [Deep Ultraviolet (DUV), λ ≤ 290nm] 發光二極體 (light-emitting diode, LED) 已經在各種應用中逐漸取代傳統的紫外線光源。然而，DUV LED的外部量子效率 (external quantum efficiency, EQE) 依然難以超過10%，這主要是因為DUV LED的p型導電層為摻雜鎂 (Mg-doped) 的AlxGa1-xN，而p型AlxGa1-xN受體的活化能很高（170 mev ~ 510 meV)，難以產生足夠的電洞p型氮化硼（BN高能隙（~ 6 eV)，也有很低的受體活化能 (~ 31 meV)，可以同時展現高穿透、高導電的特性，很適合用在DUV LED。為了研究p-BN的導電性，我們嘗試不同的金屬材料與退火條件也調整了p-BN的磊晶結構，並利用利用霍爾效應比較p-BN與p-GaN的導電性。我們發現，以低壓成長的3-nm InGaN接觸層，能有效降低p-BN界面的接觸電阻。;ENGLISH ABSTRACT
Ultraviolet (UV) light-emitting diodes (LEDs) have replaced conventional UV light sources in various applications. Nevertheless, deep-ultraviolet light-emitting diodes (DUV LEDs, λ ≤ 290nm) are still intensively investigated because of its low EQE remaining below 10% . In particular, AlGaN alloys have been the most common material for DUV LEDs. In spite of continuous efforts to develop an AlGaN DUV LED, its EQE is still typically below 10%. The limitation roots in the low conductivity of p-AlxGa1-xN as its activation energy for Mg acceptor is very high (170meV to 510meV) . The high activation energy of Mg acceptor leads to low hole injection efficiency. Among many approaches have been utilized to enhance DUV LEDs’s EQE, Boron Nitride (BN) has emerged as a promising candidate to substitute p-type AlGaN in DUV LEDs. Due to its layered structure, BN has high chemical and thermal stability. Besides that, with large bandgap (~6eV), it becomes a suitable material to be used as an electron blocking layer by causing a large conduction band offset and a smaller valence band offset with other III-V materials [8,9]. The most outstanding property of BN is the dramatic reduction of Mg acceptor energy level, which can be as low as 30meV . It will subsequently lower the resistivity of the p-type BN layer and also increase the hole concentration efficiency. These advantages are expected to enhance the EQE of the DUV LEDs. To investigate the electrical property of p-BN, we tried to fabricate ohmic contact on p-BN by different metallizatione schemes, annealing conditions, contact layers. The temperature-dependence Hall effect measurements are conducted to estimate the activation energy of acceptors of p-type GaN, with the attempt to attain similar results from p-BN. Our studies showed that the growth pressure of the InGaN contact layer plays an important role on the contact check resistance of the Au/Ni/p-BN interface.
|Appears in Collections:||[光電科學研究所] 博碩士論文|
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