大束流离子注入形成P-Si CoSi2/Si肖特基结的电学特性

采用金属离子注入法形式 Co Si2 /Si肖特基结并分析电学特性。分别测量不同退火条件下样品的 I-V、C-V特性 ,得出了各样品的势垒高度、串联电阻和理想因子。结果表明 ,采用快速热退火方法形成的结性能较好     

固相反应制备的多晶和外延CoSi2/n-Si(111)接触的肖特基特性

通过硅(111)衬底淀积的单层Co或Co/Ti双金属层在不同退火温度的固相反应,在硅上形成制备了多晶和外延CoSi2薄膜.用电流-电压和电容-电压(I-V/C-V)技术在90K到室温的温度范围内测量了CoSi2/Si肖特基接触特性. 用肖特基势垒不均匀模型分析了所测得的I-V特性,在较高温度下(≥～200K)或较低温度的较大偏压区域,I-V曲线能用热激发和在整个结面积上势垒高度的高斯分布模型描述. 而在较低温度的较小偏压区域,电流由流过一些小势垒高度微区的电流决定,从而在低温I-V曲线上在约10-7A处有一个"曲折”. 在室温下,从I-V曲线得到的多晶CoSi2/Si的势垒高度为约0. 57eV. 对外延CoSi2,势垒高度依赖于最后退火温度,当退火温度从700℃升到900℃,势垒高度从0. 54eV升高到0. 60eV.     

超薄外延CoSi2/n-Si的肖特基势垒接触特性

研究了超薄(～10nm)CoSi2/Si的肖特基势垒接触特性.Co(3-4nm)/Ti(1nm)双层金属通过快速热退火在Si(100)衬底上形成超薄CoSi2薄膜.X射线衍射测试表明该薄膜具有较好的外延特性.用I-V、C-V方法在82-332K温度范围内测试了CoSi2/Sj的肖特基势垒特性.用弹道电子发射显微术直接测量了微区肖特基势垒高度.测试表明,用Co/Ti/Si方法形成的超薄CoSj2/Sj接触在室温时具有优良的肖特基势垒特性,I-V方法测得的势垒高度为0.59eV,其理想因子为1.01;在低温时,I-V方法测得的势垒高度随温度降低而降低,理想因子则升高.采用肖特基势垒不均匀性理论,并假设势垒高度呈高斯分布,实验数据和理论吻合较好.     

超薄外延CoSi_2/n-Si的肖特基势垒接触特性

研究了超薄(～10nm)CoSi2/Si的肖特基势垒接触特性.Co(3—4nm)/Ti(1nm)双层金属通过快速热退火在Si(100)衬底上形成超薄CoSi2薄膜.X射线衍射测试表明该薄膜具有较好的外延特性.用I-V、C-V方法在82—332K温度范围内测试了CoSi2/Si的肖特基势垒特性.用弹道电子发射显微术直接测量了微区肖特基势垒高度.测试表明,用Co/Ti/Si方法形成的超薄CoSi2/Si接触在室温时具有优良的肖特基势垒特性,I-V方法测得的势垒高度为0.59eV,其理想因子为1.01;在低温时,I-V方法测得的势垒高度随温度降低而降低,理想因子则升高.采用肖特基势垒不均匀性理论,并假设势垒高度呈高斯     

退火温度对Au/Ti/4H-SiC肖特基接触特性的影响

采用电子束蒸发法在4H-SiC表面制备了Ti/Au肖特基电极,研究了退火温度对Au/Ti/4H-SiC肖特基接触电学特性的影响.对比分析了不同退火温度下样品的电流密度-电压(J-V)和电容-电压(C-V)特性曲线,实验结果表明退火温度为500℃时Au/Ti/4H-SiC肖特基势垒高度最大,在.J-V测试和C-V测试中分别达到0.933 eV和1.447 eV,且获得理想因子最小值为1.053,反向泄漏电流密度也实现了最小值1.97×10-8 A/cm2,击穿电压达到最大值660 V.对退火温度为500℃的Au/Ti/4H-SiC样品进行J-V变温测试.测试结果表明,随着测试温度的升高,肖特基势垒高度不断升高而理想因子不断减小,说明肖特基接触界面仍然存在缺陷或者横向不均匀性,高温下的测试进一步证明肖特基接触界面还有很大的改善空间.     

SiO2/4H-SiC界面氮化退火

通过1 300℃高温干氧热氧化法在n型4H-SiC外延片上生长了厚度为60 nm的SiO2栅氧化层.为了开发适合于生长低界面态密度和高沟道载流子迁移率的SiC MOSFET器件产品的栅极氧化层退火条件,研究了不同退火条件下的SiO2/SiC界面电学特性参数.制作了MOS电容和横向MOSFET器件,通过表征SiO2栅氧化层C-V特性和MOSFET器件I-V特性,提取平带电压、C-V磁滞电压、SiO2/SiC界面态密度和载流子沟道迁移率等电学参数.实验结果表明,干氧氧化形成SiO2栅氧化层后,在1 300℃通入N2退火30 min,随后在相同温度下进行NO退火120 min,为最佳栅极氧化层退火条件,此时,SiO2/SiC界面态密度能够降低至2.07×1012 cm-2·eV-1@0.2 eV,SiC MOSFET沟道载流子迁移率达到17 cm2·V-1·s-1.     

不同退火温度对4H SiC 金半接触的影响

采用高真空电子束蒸发法制作了基于4H SiC外延材料的肖特基二极管,其中欧姆接触材料为Ti/Ni,肖特基接触材料为Ni。常温下,电流-电压(I-V)测试表明Ni/4H SiC肖特基二极管具有良好的整流特性,热电子发射是其主要输运机理。对比分析不同快速退火温度下器件的I-V特性,实验结果表明875 ℃退火温度下欧姆接触特性最好,400 ℃退火温度下器件肖特基接触I-V特性最好,理想因子为1.447,肖特基势垒高度为1.029 eV。     

中波碲镉汞光电二极管pn结特性研究

采用液相外延(LPE)生长的中波Hg Cd Te薄膜,基于B离子注入n-on-p平面结技术,制备了LBIC测试结构和I-V测试芯片并进行了相应的测试和分析。LBIC测试结果表明,Hg Cd Te pn结实际结区尺寸扩展4~5?m,这主要与光刻、B离子注入以及注入后低温退火等器件工艺有关。二极管器件C-V和I-V特性研究表明,所制备的Hg Cd Te pn结不是突变结也不是线性缓变结。中波Hg Cd Te二极管器件最高动态阻抗大于30 G?,器件优值R0A高达1.21×105?cm2,表现出较好的器件性能。     

低真空退火对GaN MSM紫外探测器伏安特性的影响

利用金属有机化学气相沉积生长的非故意掺杂GaN单晶制备了金属一半导体一金属交叉指型肖特基紫外探测器。用肖特基势垒的热电子发射理论研究了低真空下不同热退火条件对器件伏安特性的影响。Au-GaN肖特基势垒由退火前的0．36eV升高到400℃0．5h的0．57eV,退火延长为1h势垒反而开始下降。分析结果表明：由工艺造成的填隙Au原子引入的缺陷是器件势垒偏低的主要原因,Au填充N空位形成了施主型杂质是退火后势垒升高的主要原因。     

GaN基肖特基器件中的反常电容特性

研究了测试频率为0.3～1.5MHz时GaN基肖特基器件的电容特性.实验发现,在Au/i-GaN肖特基器件的电容-电压(C-V)特性曲线中,出现了峰和负值电容,而Au/i-Al0.45Ga0.55N肖特基器件的C-V特性曲线中则既没有峰也没有负值电容的出现.对肖特基器件的电流-电压(I-V)特性和C-V特性进行参数提取和分析后认为,负值电容和峰的出现源于界面态的俘获和损耗,但较大的串联电阻将减弱界面态的作用.     

Investigations on Au,Ag, and Al schottky diodes on liquid encapsulated czochralski grown n-GaAs〈100〉

The Schottky barrier heights of metals Au, Ag, and Al fabricated by vacuum vapor deposition on liquid encapsulated Czochralski (LEC) grown undoped ntype GaAs (n = 2.35 × 10¹⁵ cm⁻³) were measured with current-voltage (I-V) and capacitance-voltage (C-V) techniques. Good ohmic contacts were obtained through an after deposition anneal at 430°C for two minutes in an argon gas atmosphere. In the as-deposited state, Au, Ag, and Al gave very similar I-V characteristics for n-type substrates with the barrier height qϕ_b = 0.81-1.16 eV and ideality factor n = 1.02-1.15. The C-V measurement also gives the same value of barrier height. The distribution of carrier concentration along the radial distance of the wafer is of‘M’ shape. The Al/GaAs interfaces give the nonideal rectification behavior. The Au/GaAs interfaces give the near ideal rectification behavior. The barrier height of this interface is 0.89-0.92 eV and the ideality factor is about 1.10–1.19. Electron traps in the wafer have been found by constant capacitance deep level transient spectroscopy (CC-DLTS). Mainly the EL2, EL6, and EL3 (EI1) trap levels are prominent.     

超薄的金属/LB绝缘膜/半导体结构的CV和I-V特性

本文研究了超薄的金属/LB绝缘膜/半导体(MLS)结构的C-V和I-V特性,理论分析与实验结果相一致,结论如下:(1)超薄MLS结构具有正常的C-V特性和I-V特性;(2)以LB薄膜作为绝缘层可调整肖特基器件势垒高度。     

Electrical transport and current properties of rare-earth dysprosium Schottky electrode on p-type GaN at various annealing temperatures

The electrical and current transport properties of rapidly annealed Dy/p-GaN SBD are probed by I-V and C-V techniques. The estimated barrier heights (BH) of as-deposited and 200℃ annealed SBDs are 0.80 eV (I-V)/0.93 eV (C-V) and 0.87 eV (I-V)/1.03 eV (C-V). However, the BH rises to 0.99 eV (I-V)/ 1.18 eV(C-V) and then slightly deceases to 0.92 eV (I-V)/1.03 eV (C-V) after annealing at 300℃ and 400℃. The utmost BH is attained after annealing at 300℃ and thus the optimum annealing for SBD is 300℃. By applying Cheung''s functions, the series resistance of the SBD is estimated. The BHs estimated by I-V, Cheung''s and Ψ_S-V plot are closely matched; hence the techniques used here are consistency and validity. The interface state density of the as-deposited and annealed contacts are calculated and we found that the N_SS decreases up to 300℃ annealing and then slightly increases after annealing at 400℃. Analysis indicates that ohmic and space charge limited conduction mechanisms are found at low and higher voltages in forward-bias irrespective of annealing temperatures. Our experimental results demonstrate that the Poole-Frenkel emission is leading under the reverse bias of Dy/p-GaN SBD at all annealing temperatures.     

Capacitance-frequency Spectrum Characterization of Organics/Metal Schottky Diodes

An organics/metal Schottky diode is fabricated using 3, 4： 9, 10-perylenetetracarboxylic- dianhydride（PTCDA） thin film sandwiched between ITO and Au by simple thermal evaporation technique. The current-voltage（I-V） characteristics are investigated at room temperature in open air. The results show the rectification ratio is in excess of 100. From the capacitance-frequency（C-f） and capacitance-voltage（C-V） measurements, the Schottky barrier height between 0.2-0.3 eV is obtained according to standard Schottky theory.     

Aluminum schottky contacts to n-type 4H-SiC

Aluminum Schottky contacts to n-type 4H-SiC were fabricated, and the results of electrical measurements on the devices are presented along with the Schottky barrier height and ideality factor. Furthermore, two different samples having different surface treatments were investigated. The barrier heights obtained from current-voltage (I-V) measurements on both samples are essentially identical, with an average value of 0.64 eV. The ideality factor of Sample 2, which had an HF-dip surface treatment, had an average value of 1.66. The ideality factor of Sample 1, which had a surface treatment similar to the other sample but with the addition of an RCA-like clean, had an average value of 2.60. Measurements on some control devices with Au contacts showed that no significant Fermi-level pinning occurred, and the barrier-height results for all devices approached the Schottky-Mott limit. Capacitance-voltage (C-V) measurements on the Al devices from Sample 1 yielded barrier heights that were much smaller than those obtained from the I-V curves; however, for Sample 2, the barrier heights obtained from both C-V and I-V methods were comparable. Based on these results, we propose a model that accounts for the measured results in terms of a thin interfacial layer produced in Sample 1, which screens the depletion region from the applied electric field. This model yields a possible explanation of how the two surface treatments results in devices with the same barrier height but different ideality factors. The results in this paper represent some of the first experimental data on Al/4H-SiC Schottky contacts.     

/sup 60/Co gamma irradiation effects on n-GaN Schottky diodes

The effect of /spl gamma/-ray exposure on the electrical characteristics of nickel/n-GaN Schottky barrier diodes has been investigated using current-voltage (I-V), capacitance-voltage (C-V), and deep-level transient spectroscopy (DLTS) measurements. The results indicate that /spl gamma/-irradiation induces an increase in the effective Schottky barrier height extracted from C-V measurements. Increasing radiation dose was found to degrade the reverse leakage current, whereas its effect on the forward I-V characteristics was negligible. Low temperature (/spl les/50) post-irradiation annealing after a cumulative irradiation dose of 21 Mrad(Si) was found to restore the reverse I-V characteristics to pre-irradiation levels without significantly affecting the radiation-induced changes in C-V and forward I-V characteristics. Three shallow radiation-induced defect centers with thermal activation energies of 88 104 and 144 meV were detected by DLTS with a combined production rate of 2.12 /spl times/ 10/sup -3/ cm/sup -1/. These centers are likely to be related to nitrogen-vacancies. The effect of high-energy radiation exposure on device characteristics is discussed taking into account possible contact inhomogeneities arising from dislocations and interfacial defects. The DLTS results indicate that GaN has an intrinsically low susceptibility to radiation-induced material degradation, yet the effects observed in the Schottky diode I-V and C-V characteristics indicate that the total-dose radiation hardness of GaN devices may be limited by susceptibility of the metal-GaN interface to radiation-induced damage.     

RuO2/GaN Schottky contact formation with superiorforward and reverse characteristics

This is a first time report of a ruthenium oxide (RuO₂) Schottky contact on GaN. RuO₂ and Pt Schottky diodes were fabricated and their characteristics compared. When the RuO₂ Schottky contact was annealed at 500°C for 30 min, the current-voltage (I-V) and capacitance-voltage (C-V) characteristics of the RuO₂ were dramatically improved. The annealed RuO₂ /GaN Schottky contact exhibited a reverse leakage current that was at least two or three orders lower in magnitude than that of the Pt/GaN contact along with a very large barrier height of 1.46 eV, which is the highest value ever reported for a GaN Schottky system     

Schottky barriers on n-GaN grown on SiC

Characteristics of Schottky barriers fabricated on n-type GaN were investigated. The barriers were formed by vacuum thermal evaporation of Cr, Au, and Ni. Current-voltage (I-V) and capacitance-voltage (C-V) characteristics of the barriers were measured in a wide temperature and current density range. Fundamental parameters (barrier height and built-in potential) of the Schottky barriers were determined. The dependence of the barrier ideality factor on doping concentration in GaN was measured. Correlation between the barrier height and metal work function was observed. The electron affinity for GaN was determined using both C-V and I-V characteristics. The current flow mechanism through the barriers is discussed.     

Correlation between Interfacial Oxides and Electrical Characteristics of GaN Schottky Diodes

The electrical characteristics of GaN schottky diode with and without the interracial oxides are compared in this paper. The influence of interracial oxides on the electrical characteristics of the schottky diodes has been confirmed by the I-V, C-V measures. We find the barrier height have a reduction of 0.05 eV- 0.1 eV. There is an interracial insulating oxide with the thickness of 0. 05 nm- 0. 1 nm after conventional cleaning. Either the forward or the backward currents increase. The backward punch through voltages are reduced to 50% and the capacitances have increased by 100%.