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AlGaN/GaN Schottky Barrier Diodes for High Power and Fast Switching Applications : 고 전력과 고속 스위칭 응용을 위한 AlGaN/GaN 쇼트키 접합 다이오드
DC Field | Value | Language |
---|---|---|
dc.contributor.advisor | 서광석 | - |
dc.contributor.author | Namcheol Jeon | - |
dc.date.accessioned | 2017-07-13T07:12:06Z | - |
dc.date.available | 2017-07-13T07:12:06Z | - |
dc.date.issued | 2015-08 | - |
dc.identifier.other | 000000067525 | - |
dc.identifier.uri | https://hdl.handle.net/10371/119134 | - |
dc.description | 학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2015. 8. 서광석. | - |
dc.description.abstract | In recent years, aluminum gallium nitride (AlGaN)/ gallium nitride (GaN) heterostructure devices have received great attention as high efficiency power devices due to their superior properties, such as high current density, high breakdown field, and fast recovery time. This dissertation presents the investigations of AlGaN/GaN Schottky barrier diodes (SBDs) and high electron mobility transistors (HEMTs) as a power switching devices.
Schottky HEMTs were fabricated on the AlGaN/GaN heterostructure with a silicon carbon nitride (SiCN) capping layer. With a 5-nm-thick SiCN capping layer, two-dimensional electron gas (2DEG) carrier concentration was increased about 51 % compared with a conventional AlGaN/GaN heterostructure, due to the neutralization of negative polarization charges at the AlGaN surface. Thus, maximum drain current of the Schottky HEMT with SiCN capping layer was increased about 10 % compared with a conventional Schottky HEMT. Schottky HEMT with an integrated Schottky-drain protection diode was fabricated. Low turn-on voltage of 0.7 V and blocking capability over 100 V was measured with a SiCN-SBD. Recessed Schottky contact was studied as an AlGaN/GaN SBD scheme. Two-step etching composed of dry etching and wet digital etching with 5 nm/cycle etch rate was proposed as an epi-layer etching method. Due to the surface treatment of wet digital etching, the ideality and Schottky barrier height of SBDs were improved from 1.35 and 0.60 eV to 1.19 and 0.73 eV, respectively. Influence of anode recess depth was analyzed and optimum recess depth was determined. As a result, the AlGaN/GaN SBD with turn-on voltage of 0.52 V, ideality factor of 1.17, Schottky barrier height of 0.76 eV, forward current of 127 mA/mm at 1.5 V, and reverse current of 2 μA/mm at -1100 V was fabricated. Failure of the fabricated diode was not observed at the 200 °C, 200 V reverse stress condition during 200 hours. Double field plate structure to increase the breakdown voltage of AlGaN/GaN SBD was also studied. The electric field distribution effect of the field plates was clearly verified by device simulation. Experimental result shows the increase of breakdown voltage from 925 V to 1065 V with the double field plate structure. AlGaN/GaN SBD with anode edge terminated SiNx layer was proposed to reduce the reverse current. Reverse leakage current of the proposed diode was decreased about 103 order due to the suppression of the surface current. The fabricated diodes shows the good forward and reverse current uniformity. The multi-finger lateral-type AlGaN/GaN SBDs were successfully implemented with a 5 mm2 active area. The fabricated diode exhibits the forward current of 7.1 A at 1.5 V, specific on-resistance of 6.1 mΩ·cm2, reverse current of 12.5 µA at -600 V, and breakdown voltage of 1080 V. The figure of merit (VBR2/Ron) is 192 MW/cm2, which is one of the highest value of the lateral-type large area GaN SBDs ever published. Reverse recovery time of the fabricated diode was measured as 10 ns. These results indicate that the proposed AlGaN/GaN SBDs are adequate for fast switching applications with low losses. | - |
dc.description.tableofcontents | Chapter 1 Introduction 1
1.1 Demand on high efficiency power devices 1 1.2 GaN material properties 5 1.3 Substrates for epitaxy of GaN 8 1.4 AlGaN/GaN heterostructure 10 References of chapter 1 13 Chapter 2 Review of GaN Power Schottky Barrier Diodes 16 2.1 GaN power device module 16 2.2 GaN power SBD requirements and issues 19 2.3 GaN SBD schemes 21 2.4 SBD and HEMT on AlGaN/GaN heterostructure with SiCN capping layer 25 2.4.1 Introduction 25 2.4.2 Characteristics of epi-wafer 26 2.4.3 AlGaN/GaN HEMT with a SiCN cap layer (SiCN-HEMT) 28 2.4.4 AlGaN/GaN HEMT with an integrated Schottky-drain protection diode 30 2.5 Recessed SBD and motivation of study 34 References of chapter 2 38 Chapter 3 Low Damage Digital Etching 43 3.1 An overview of digital etching 43 3.2 Development of wet digital etching technique 48 3.3 Hall-effect measurement 52 3.4 The effects of digital etching on recessed SBDs 57 3.5 The effects of digital etching on Schottky HEMTs 63 References of chapter 3 73 Chapter 4 Recessed AlGaN/GaN SBD 78 4.1 Introduction 78 4.2 Influence of anode recess depth of AlGaN/GaN SBD 79 4.2.1 Device fabrication 79 4.2.2 I-V characteristics 82 4.2.3 C-V characteristics 93 4.2.4 Reliability test 94 4.3 SBD with double field plate 96 4.3.1 Fabrication and simulation 96 4.3.2 Measurement results 99 4.4 Large area GaN SBD with fully recessed anode 102 References of chapter 4 110 Chapter 5 AlGaN/GaN SBD with Anode Edge Termination 114 5.1 Introduction 114 5.2 Redeposition process with SF6 plasma treatment 118 5.2.1 Process description 118 5.2.2 Development of low power SF6 plasma treatment 119 5.2.3 Schottky HEMT with redeposition process 123 5.3 AlGaN/GaN SBD with anode edge terminated SiNx layer 129 5.3.1 Unit SBD fabrication 129 5.3.2 Unit SBD measurement results 132 5.3.3 Large area GaN SBD with edge termination 139 References of chapter 5 142 Chapter 6 Thin-Film Based Packaging Technology 145 6.1 Introduction 145 6.2 Improvement of BCB adhesion on Cr/Au metal layer 146 6.3 Stress compensation 151 References of chapter 6 154 Chapter 7 Conclusion and Future Works 158 Abstract in Korean 161 | - |
dc.format | application/pdf | - |
dc.format.extent | 5838683 bytes | - |
dc.format.medium | application/pdf | - |
dc.language.iso | en | - |
dc.publisher | 서울대학교 대학원 | - |
dc.subject | Power device | - |
dc.subject | GaN | - |
dc.subject | AlGaN/GaN heterostructure | - |
dc.subject | Schottky barrier diode (SBD) | - |
dc.subject | High electron mobility transistor (HEMT) | - |
dc.subject | Recess etching | - |
dc.subject | Passivation | - |
dc.subject | Silicon nitride (SiNx) | - |
dc.subject | On-resistance | - |
dc.subject | Breakdown | - |
dc.subject | Pulsed I-V | - |
dc.subject | Edge termination | - |
dc.subject.ddc | 621 | - |
dc.title | AlGaN/GaN Schottky Barrier Diodes for High Power and Fast Switching Applications | - |
dc.title.alternative | 고 전력과 고속 스위칭 응용을 위한 AlGaN/GaN 쇼트키 접합 다이오드 | - |
dc.type | Thesis | - |
dc.contributor.AlternativeAuthor | 전남철 | - |
dc.description.degree | Doctor | - |
dc.citation.pages | xiv, 163 | - |
dc.contributor.affiliation | 공과대학 전기·컴퓨터공학부 | - |
dc.date.awarded | 2015-08 | - |
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