在這研究中，我們直接成長分子束磊晶的氧化鉿在未使用介面鈍化層或經化學處理的砷化鎵基板上。並且使用原子層化學氣相沉積的氧化鋁作為保護層沉積在氧化鉿上避免水氣吸收。將樣品進行系統性地退火並量測電容電壓特性，樣品呈現良好的電容電壓特性並擁有低的介面缺陷密度以及高的熱穩定性。在p型基板的金氧半電容退火條件為在氮氣環境300度 10分鐘550度10分鐘，接著在氦氣環境進行900度60秒高溫退火，而在n型基板的金氧半電容退火條件為在氮氣環境550度20分鐘，接著在氦氣環境進行900度30秒高溫退火。將樣品在400度使用混合氣體退火5分鐘，p型基板的金氧半電容在聚積區域的頻率分散(500Hz-1MHz)為5%，n型基板的金氧半電容則為11.9%。
此外，使用準靜態電容電壓量測技術萃取出來的介面缺陷密度在中間能隙附近無峰型分佈。在中間能隙位置的介面缺陷密度為4.7×1011 eV-1cm-2，最低的介面缺陷密度的值為1.4×1011eV-1cm-2落在價電帶上方0.3電子伏特的位置。而使用電導方法所量測出來的介密缺陷密度在價電帶上方0.35電子伏特的位置為1.8×1011eV-1cm-2。在這研究中，有著低介面缺陷密度以及高熱穩定性的的氧化鉿/砷化鎵系統有著很高的潛力能做出具有出色表現的砷化鎵金氧半電晶體

In this study, MBE-HfO2 was in-situ deposited on freshly-grown GaAs without using interfacial passivation layers and chemical treatments. An ALD-Al2O3 film was subsequently deposited on MBE-HfO2 as a protecting layer against moisture from atmosphere. Systematic annealing process is adopted to samples and shows excellent C-V characteristics with low Dit and high thermal stability. The MOSCAPs of MBE-HfO2/GaAs were initially post deposition annealed at 300oC 10min 550oC 10min in N2 followed by 900oC 60s in He for p-type and 550oC 20min in N2 followed by 900oC 30s in He for n-type. The MOSCAPs were further improved by post metallization annealing at 400oC 5min in forming gas, which has shown small frequency dispersion 5.8% (500Hz-1MHz) at accumulation region for p-MOSCAPs, and 11.9% for n-MOSCAPs. Furthermore, Dit spectrum extracted from QSCV method showed no peak profile near midgap region. The Dit near midgap region is given by 4.7×1011eV-1cm-2 and a minimum value of 1.4×1011eV-1cm-2 located at 0.3eV above valence band edge is observed. The Dit value of 1.8×1011eV-1cm-2 located at 0.35eV above valence band edge is given by conductance method. The high thermal stability and low interfacial trap density attained in this experiment shows the high potential of MBE-HfO2/GaAs system to realize high performance enhance mode GaAs MOSFETs.

Table of Content.............................................VI
中文摘要......................................................IX
Abstract......................................................X
Table Captions..............................................XII
Figure Captions...........................................XIIII
Chapter 1 Introduction........................................1
1.1 Background................................................1
1.2 High-κ Dielectrics on III-V Compound Semiconductors.......6
1.3 Motivation................................................9
Chapter 2 Theory and Instrumentations........................11
2.1 MBE System...............................................11
2.1.1 Molecular Beam Epitaxy (MBE)...........................11
2.1.2 Reflection High Energy Electron Diffraction (RHEED)....13
2.2 Atomic Layer Deposition..................................14
2.3 Metal-Oxide-Semiconductor (MOS) capacitor................16
2.3.1 Electrical measurement.................................16
2.3.2 Ideal C-V Characteristics..............................18
2.3.2 Different Types of Oxide Charges.......................22
2.4 Extraction of Interfacial Trap of Densities..............24
2.4.1 Terman Method..........................................24
2.4.2 Quasi-static Capacitance-Voltage (QSCV) Measurement....24
2.4.3 Conductance method.....................................26
2.5 Extraction of Electrical Parameters from C-V Curves......28
2.5.1 Substrate Doping Concentration.........................28
2.5.2 Flat-Band Voltage (VFB)................................29
3.1 Film Deposition in UHV Multi-Chamber system..............31
3.1.1 Sample Preparation.....................................31
3.1.2 III-V Semiconductor Layers Deposition..................32
3.1.3 Oxide Deposition.......................................33
3.2 Annealing Treatment......................................34
3.3 Electrical Properties Measurement........................35
Chapter 4 Result and Discussion..............................37
4.1 Electrical Characteristics of GaAs MOSCAPs Passivated by MBE Deposition HfO2..............................................37
4.1.1 Medium Temperature Annealing Effect on MBE-HfO2/p-GaAs.37
4.1.2 Low Temperature Annealing Effect and the Duration at Medium Temperature Annealing Effect on MBE-HfO2/p-GaAs..............45
4.1.3 C-V Characteristics of MBE-HfO2/p-GaAs(001) under Various High temperature Annealing Condition.........................51
4.1.4 Effect of Annealing at Different Temperature...........56
4.1.5 C-V Characteristics of MBE-HfO2/GaAs(001) under Various Annealing Condition..........................................59
4.2 Comparison of MBE-HfO2, MBE-Y2O3 and ALD-Y2O3 on GaAs in C-V and Dit distribution.........................................64
Chapter 5 Conclusion.........................................69
References...................................................72

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