JAEA-Review-2010-065.pdf:15.99MB - 日本原子力研究開発機構

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1-06 Study of Ion-Implantation Condition Effects for AlGaN/GaN-Based Light Emitting Device H. Okada a) , T. Hata a) , M. Kondo a) , Y. Furukawa a) , A. Wakahara a) , S. Sato b) and T. Ohshima b) a) Toyohashi University of Technology, b) Environment and Industrial Materials Research Division, QuBS, JAEA Effects of ion-implantation conditions were studied for new type light emitting device based-on AlGaN/GaN high electron mobility transistor (HEMT) structure having selective doping of Eu in the channel of the transistor. Drastic decrease of the channel conductance was observed in Eu implanted samples. This decrease is explained by decrease of electron mobility, rather than decrease of the sheet carrier density from Hall effect measurement. It was confirmed that the clear red electroluminescence observed in the fabricated device originated from Eu ion with luminescence peak at 620 nm suggesting 5 D0→ 7 F2 transition in Eu. The results suggest that ion-implantation condition affects electrical and electroluminescence properties of the proposed light emitting device. 我々は窒化物半導体ヘテロ構造である AlGaN/GaN 高電子移動度トランジスタ(HEMT)構造にイオン注入法により希土類元素を添加した三端子型発光素子を提案・試作し、その発光を報告している 1) 。このデバイスは希土類元素の内殻遷移に基づく発光を利用するもので、単色性に優れ、温度消光が少ない発光デバイスが期待でき、光通信素子、光を使った分析装置に有用な発光素子を実現できる。これまで、デバイス試作時に用いたイオン注入条件は、過去に行ったフォトルミネセンス(PL)やカソードルミネセンス(CL)などの光励起法による発光特性の結果を参照して設定してきたが、電流注入発光(EL)素子として良好な特性を実現するためには、デバイス作製条件と電気的特性・発光特性との関連を検討する必要がある。今回、希土類元素のイオン注入量、加速エネルギーと、素子の電気的特性、発光特性との関係に注目し、検討を行った。今回の素子作製には有機金属化学気相成長法により Si 上にエピタキシャル成長させた AlGaN/GaN ウェハを用いた。室温におけるシートキャリア濃度は 1 × 10 13 cm -2 、移動度は 1,450 cm 2 /Vs であった。まず反応性イオンエッチングにより素子領域を分離する。次にイオン注入の保護膜として形成した SiO 2 層の一部に注入窓をエッチングにより形成した。試料への Eu イオン注入には、TIARA の 400 kV イオン注入装置を使用した。その後注入による欠陥の回復熱処理を行い、保護膜の SiO 2 をエッチングにより除去しソース・ドレイン電極を電子ビーム蒸着とリフトオフにより形成した。最後にゲートを同様に形成した。 Table 1 にチャネルコンダクタンス g の測定結果を示す。チャネルコンダクタンスは Eu イオン注入により大幅に減少した。この高抵抗化は注入量の増加とともにより顕著に現れた。Eu 注入量 1 × 1016 cm -2 では若干コンダクタンスの上昇が見られているが、この原因は不明である。イオン注入による高抵抗化の要因について検討するために、Van der Pauw 法によるホール効果測定を行った。Eu ドーズ量を変化させたサンプルについて評価したところ、シートキャリア濃度は 10 14 ~10 16 cm -2 のドーズ量に対して大きな変化はみられず、ドーズ量の増加とともに電子移動度の低下がみられた。この振る舞いは、HEMT のチャネルコンダクタンスから見積 JAEA-Review 2010-065 - 10 - もった実効移動度と数値的にもよく一致した。適切な注入量の設定により、注入領域の高抵抗化による電界集中が生じ、加速された電子による Eu イオンの衝突励起発光を引き起こすことができると考えられる。次に、作製したデバイスの EL 発光特性について評価した。ソース-ドレイン間バイアス V DS = 100 V により注入部分に赤色発光が得られた。注入量を変化させた実験から、注入量の増加とともに明確な赤色発光が認められることがわかった。Fig. 1 に加速エネルギー 200 keV、注入量 1 × 1015 cm -2 の条件で作製したデバイスの EL 発光写真を示す。分光器によるスペクトル分析から、Eu イオンの内殻遷移 5 D 0→ 7 F 2 に対応する 620 nm 付近にピークをもつスペクトルが得られ、作製したデバイスにおいて希土類元素からの発光が得られていることが確認できた。今後、ここで得られたイオン注入条件や、デバイス構造、作製条件の最適化により、希土類元素の発光に基づくユニークな発光素子の高効率化を行う。 Table 1 Eu dose dependence on channel conductance of fabricated FET with Vacc=70 keV. Eu dose [cm -2 ] g [μS] No implantation 7,000 1 × 1013 1 × 10 14 1 × 10 15 1 × 10 16 190 37.1 31.7 62.4 Fig. 1 Electroluminescence (EL) image of fabricated device (VDS = 100 V, VGS = 0 V). Reference 1) H. Okada et al., Phys. Status Solidi C6 S2 (2009) S631-634.
Total Ionizing Dose Tolerance of SiC Buried Gate Static Induction Transistors up to 10 MGy S. Onoda a) , Y. Tanaka b) , A. Takatsuka b) , T. Yatsuo b) and T. Ohshima a) a) Environment and Industrial Materials Research Division, QuBS, JAEA, b) National Institute of Advanced Industrial Science and Technology Silicon Carbide (SiC) is regarded as one of the candidate materials for devices with radiation hardness, owing to its superior radiation resistance as well as excellent physical 1) properties and chemical stability. Ohshima et al. reported that the electrical properties for 6H-SiC Metal-Oxide Field Effect Transistors (MOSFETs) with steam-annealed gate oxide did not degrade by gamma-ray irradiation at 200 kGy in spite that H2-annealed ones showed the degradation above 40 kGy. These results suggest that the ionizing radiation response of MOSFETs is strongly affected by their fabrication processes especially gate oxidation. Instead of SiC MOSFETs, in this study, the Total Ionizing Dose (TID) effects on SiC Buried Gate Static Induction Transistors Change in On-voltage ( V ) Change in Breakdown-voltage ( V ) 1-07 6 5 4 3 2 1 0 -1 -2 0 2 4 6 8 10 100 0 -100 -200 -300 Absorbed Dose ( MGy ) -400 Si IGBT -500 Si MOSFET SiC-SIT -600 0 2 4 6 8 10 Absorbed Dose ( MGy ) Si IGBT Si MOSFET SiC-SIT Fig. 1 Change in on-voltage of SiC-SIT, Si MOSFET, and Si IGBT after gamma-ray irradiation up to the absorbed dose of 10 MGy. Fig. 2 Change in breakdown voltage of SiC-SIT, Si MOSFET, and Si IGBT after gamma-ray irradiation up to the absorbed dose of 10 MGy. JAEA-Review 2010-065 - 11 - (SiC-BGSITs) involving no silicon dioxide are evaluated up to the absorbed dose of 10 MGy(SiO 2). For comparative purpose, we also evaluated the TID effects on commercial Si-MOSFET (17N80C3) and Si-IGBT (5J301). The SiC-BGSITs are developed by AIST 2, 3) for the evaluation of radiation hardness. All devices including both SiC and Si transistors were mounted in TO220 packages. The gamma-ray irradiation from 60 Co source in JAEA was performed at the dose rate of 8.8 kGy(SiO 2)/h up to the total dose of 10 MGy. During the gamma-ray irradiation, the devices were floating. After each irradiation, the on-state, the threshold, and the blocking characteristics of each device were measured. The on-state characteristics were measured at the gate voltage (V G) of +15 V for Si-IGBT and Si-MOSFET and that of +2.5 V for SiC-BGSIT. The on-voltage (V on) was defined as the drain voltage (V D) at the drain current (I D) of 10 A. The threshold voltage (V th) was derived from I D-V G characteristic measured at V D of +0.3 V. The blocking characteristics were measured at V G of 0 V for Si-IGBT and Si-MOSFET and that of -10 V for SiC-BGSIT. Figure 1 and 2 show the change in on- and breakdown voltage as a function of gamma-ray absorbed dose. The V on of Si-IGBT degraded excessively at the early stage of the irradiation (>~0.1 MGy(SiO 2)) due to the bulk damage produced by Compton electrons. Although not shown here the V th of Si-MOSFET is very sensitive against the radiation. The blocking characteristics of Si-MOSFET degraded significantly against the radiation as shown in Fig. 2. The reduction in V on of Si-IGBT and the degradation of blocking characteristics of Si-MOSFET are very serious problems to use these devices for the application under high radiation environment. On the other hand, we successfully confirmed that SiC-BGSIT has very high radiation hardness and can operate stably under harsh environment. References 1) T. Ohshima et al., Mater. Sci. Forum 1093 (2002) 389-393. 2) Y. Tanaka et al., Mater. Sci. Forum 1219 (2006) 527-529. 3) Y. Tanaka et al., IEEE Elect. Dev. Lett. 908 (2006) 27. Acknowledgement This study was carried out under the Strategic Promotion Program for Basic Nuclear Research by the Ministry of Education, Culture, Sports, Science and Technology of Japan.
Page 3 and 4: JAEA-Review 2010-065 JAEA Takasaki
Page 5 and 6: JAEA-Review 2010-065 PREFACE This r
Page 7: JAEA-Review 2010-065 and pulsed hea
Page 10 and 11: JAEA-Review 2010-065 1-23 Studies o
Page 12 and 13: JAEA-Review 2010-065 3-24 Lethal Ef
Page 14 and 15: JAEA-Review 2010-065 4-07 Fabricati
Page 16 and 17: JAEA-Review 2010-065 5. Status of I
Page 18 and 19: JAEA-Review 2010-065 1-13 Alpha-rad
Page 21 and 22: 1-01 Radiation Resistance of InGaP/
Page 23 and 24: 1-03 Evaluation of Soft Error Rates
Page 25: 1-05 Heavy-ion Induced Current in S
Page 29 and 30: 1-09 Evaluation of Single Event Eff
Page 31 and 32: Hydrogen Diffusion in a-Si:H Thin F
Page 33 and 34: 1-13 Alpha-radiolysis of Organic Ex
Page 35 and 36: Study on Stability of Cs·Sr Solven
Page 37 and 38: Irradiation Effect of Gamma-Rays on
Page 39 and 40: 1-19 Development of Radiation Resis
Page 41 and 42: 1-21 Alpha-Ray Irradiation Damage o
Page 43 and 44: 1-23 Studies on Microstructure and
Page 45 and 46: 1-25 Effect of Groundwater Radiolys
Page 47 and 48: 1-27 Simulation of Neutron Damage M
Page 49 and 50: 1-29 Irradiation Hardening in Ion-i
Page 51 and 52: 1-31 Preparation of Anion-Exchange
Page 53 and 54: 1-33 Radiation-Induced Graft Polyme
Page 55: JAEA-Review 2010-065 2. Environment
Page 58 and 59: 2-02 Development of Zwitterionic Mo
Page 60 and 61: Modification of Hydroxypropyl Cellu
Page 62 and 63: The Recovery of Precious Metals Usi
Page 64 and 65: 2-08 ESR Study on Carboxymethyl Chi
Page 67 and 68: JAEA-Review 2010-065 3. Biotechnolo
Page 69 and 70: JAEA-Review 2010-065 3-28 Electron
Page 71: JAEA-Review 2010-065 3-51 PET Studi
Page 74 and 75: 3-02 Mutagenic effects of He ion pa
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3-04 Functional Analysis of Flavono
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3-06 Generation New Ornamental Plan
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3-08 Stability of Flower-colour Mut
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3-10 JAEA-Review 2010-065 Effects o
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3-12 Producing New Gene Resources i
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3-14 Production of Soybean Mutants
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Assessment of Irradiation Treatment
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3-18 Effect of Different LET Radiat
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3-20 JAEA-Review 2010-065 Fungicide
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3-22 JAEA-Review 2010-065 FACS-base
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3-24 Lethal Effects of Different LE
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3-26 JAEA-Review 2010-065 Ion Beam
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3-28 Electron Spin Relaxation Behav
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3-30 Target Irradiation of Individu
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3-32 Carbon-ion Microbeam Induces B
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3-34 Biological Effects of Carbon I
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3-36 Difference in Bystander Lethal
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3-38 Analysis of Lethal Effect Medi
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3-40 Irradiation with Carbon Ion Be
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3-42 Expression of Two Gelsolins in
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3-44 Analysis of Bystander Cell Sig
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3-46 Quantitative Evaluation of Ric
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3-48 Visualization of 107 Cd Accumu
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3-50 Uniformity Measurement of Newl
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3-52 Imaging and Biodistribution of
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3-54 Improvement of Spatial Resolut
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3-56 The Optimum Conditions in the
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3-58 Evaluation of Cisplatin Concen
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3-60 JAEA-Review 2010-065 Analysis
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3-62 JAEA-Review 2010-065 Sensitivi
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JAEA-Review 2010-065 4-14 The Effec
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JAEA-Review 2010-065 4-39 Relations
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4-01 Hydrogen Gasochromism of WO3 F
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4-03 Synthesis of Single-Crystallin
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4-05 Synergy Effects in Electron/Io
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Fabrication of Diluted Magnetic Sem
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4-09 Gas Permeation Characteristics
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4-11 Control of Radial Size of Poly
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4-13 Behavior of N Atoms in Nitridi
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4-15 JAEA-Review 2010-065 Annealing
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Low Temperature Ion Channeling of F
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4-19 Radiation-Induced Electrical D
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4-21 Study on Cu Precipitation in E
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4-23 Evaluation of Fluorescence Mat
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4-25 Evaluation of the ZrC Layer fo
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4-27 Structure Analysis of K/Si(111
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4-29 LET Effect on the Radiation In
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4-31 Stabilization of Measurement S
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Systematic Measurement of Neutron a
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4-35 Measurement of Neutron Fluence
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4-37 Evaluation of the Response Cha
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4-39 Relationship between Internucl
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4-41 Analysis of Radiation Damage a
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4-43 Positive Secondary Ion Emissio
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4-45 JAEA-Review 2010-065 Ion Induc
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4-47 Fabrication of Dielectrophoret
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4-49 Fast Single-Ion Hit System for
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4-51 Development of Beam Generation
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JAEA-Review 2010-065 5. Status of I
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Operation of the AVF Cyclotron T. N
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Operation of Electron Accelerator a
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5-06 FACILITY USE PROGRAM in Takasa
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5-08 Radioactive Waste Management i
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Appendix 2 List of Related Patents
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Appendix 4 Type of Research Collabo
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表1.SI 基本単位基本量 SI
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