排序方式: 共有106条查询结果,搜索用时 15 毫秒
1.
本文采用导模法生长技术,成功制备了高质量掺Si氧化镓(β-Ga2O3)单晶,掺杂浓度为2×1018 cm-3.晶体呈现淡蓝色,通过劳厄衍射、阴极荧光(CL)及拉曼测试对晶体的基本性质进行了表征,结果表明晶体质量良好.紫外透过光谱证明该晶体的禁带宽度约为4.71 eV.此外,在剥离衬底上,采用电子束蒸发、光刻和显影技术制备了垂直结构的肖特基二极管,平均击穿场强EAva为2.1 MV/cm,导通电阻3 mΩ·cm2,展示了优异性能. 相似文献
2.
3.
Comparative study of different properties of GaN films grown on(0001) sapphire using high and low temperature AlN interlayers 下载免费PDF全文
Comparative study of high and low temperature AlN
interlayers and their roles in the properties of GaN epilayers
prepared by means of metal organic chemical vapour deposition on
(0001) plane sapphire substrates is carried out by high resolution
x-ray diffraction, photoluminescence and Raman spectroscopy. It is
found that the crystalline quality of GaN epilayers is improved
significantly by using the high temperature AlN interlayers, which
prevent the threading dislocations from extending, especially for
the edge type dislocation. The analysis results based on
photoluminescence and Raman measurements demonstrate that there
exist more compressive stress in GaN epilayers with high temperature
AlN interlayers. The band edge emission energy increases from
3.423~eV to 3.438~eV and the frequency of Raman shift of $E_{2
}$(TO) moves from 571.3~cm$^{ - 1}$ to 572.9~cm$^{ - 1}$ when the
temperature of AlN interlayers increases from 700~$^{\circ}$C to
1050~$^{\circ}$C. It is believed that the temperature of AlN
interlayers effectively determines the size, the density and the
coalescence rate of the islands, and the high temperature AlN
interlayers provide large size and low density islands for GaN
epilayer growth and the threading dislocations are bent and
interactive easily. Due to the threading dislocation reduction in
GaN epilayers with high temperature AlN interlayers, the approaches
of strain relaxation reduce drastically, and thus the compressive
stress in GaN epilayers with high temperature AlN interlayers is
high compared with that in GaN epilayers with low temperature AlN
interlayers. 相似文献
4.
Effects of the strain relaxation of an AlGaN barrier layer induced by various cap layers on the transport properties in AlGaN/GaN heterostructures 总被引:1,自引:0,他引:1 下载免费PDF全文
The strain relaxation of an AlGaN barrier layer may be influenced by a thin cap layer above, and affects the transport properties of AlGaN/GaN heterostructures. Compared with the slight strain relaxation found in AlGaN barrier layer without cap layer, it is found that a thin cap layer can induce considerable changes of strain state in the AlGaN barrier layer. The degree of relaxation of the AlGaN layer significantly influences the transport properties of the two-dimensional electron gas (2DEG) in AlGaN/GaN heterostructures. It is observed that electron mobility decreases with the increasing degree of relaxation of the AlGaN barrier, which is believed to be the main cause of the deterioration of crystalline quality and morphology on the AlGaN/GaN interface. On the other hand, both GaN and AlN cap layers lead to a decrease in 2DEG density. The reduction of 2DEG caused by the GaN cap layer may be attributed to the additional negative polarization charges formed at the interface between GaN and AlGaN, while the reduction of the piezoelectric effect in the AlGaN layer results in the decrease of 2DEG density in the case of AlN cap layer. 相似文献
5.
基于微波等离子体化学气相淀积生长的单晶金刚石制作了栅长为2μm的耗尽型氢终端金刚石场效应晶体管,并对器件特性进行了分析.器件的饱和漏电流在栅压为-6 V时达到了96 mA/mm,但是在-6 V时栅泄漏电流过大.在-3.5 V的安全工作栅压下,饱和漏电流达到了77 mA/mm.在器件的饱和区,宽5.9 V的栅电压范围内,跨导随着栅电压的增加而近线性增大到30 mS/mm.通过对器件导通电阻和电容-电压特性的分析,氢终端单晶金刚石的二维空穴气浓度达到了1.99×10~(13)cm~(-2),并且迁移率和载流子浓度均随着栅压向正偏方向的移动而逐渐增大.分析认为,沟道中高密度的载流子、大的栅电容以及迁移率的逐渐增加是引起跨导在很大的栅压范围内近线性增加的原因. 相似文献
6.
Low power fluorine plasma effects on electrical reliability of AlGaN/GaN high electron mobility transistor 下载免费PDF全文
The new electrical degradation phenomenon of the AlGaN/GaN high electron mobility transistor(HEMT) treated by low power fluorine plasma is discovered. The saturated current, on-resistance, threshold voltage, gate leakage and breakdown voltage show that each experiences a significant change in a short time stress, and then keeps unchangeable. The migration phenomenon of fluorine ions is further validated by the electron redistribution and breakdown voltage enhancement after off-state stress. These results suggest that the low power fluorine implant ion stays in an unstable state. It causes the electrical properties of AlGaN/GaN HEMT to present early degradation. A new migration and degradation mechanism of the low power fluorine implant ion under the off-stress electrical stress is proposed. The low power fluorine ions would drift at the beginning of the off-state stress, and then accumulate between gate and drain nearby the gate side. Due to the strong electronegativity of fluorine, the accumulation of the front fluorine ions would prevent the subsequent fluorine ions from drifting, thereby alleviating further the degradation of AlGaN/GaN HEMT electrical properties. 相似文献
7.
Polar Dependence of Threading Dislocation Density in GaN Films Grown by Metal-Organic Chemical Vapor Deposition 下载免费PDF全文
We investigate the threading dislocation(TD) density in N-polar and Ga-polar GaN films grown on sapphire substrates by metal-organic chemical vapor deposition.X-ray diffraction results reveal that the proportion of screw type TDs in N-polar GaN is much larger and the proportion of edge type TDs is much smaller than that in Ga-polar.Transmission electron microscope results show that the interface between the AlN nucleation layer and the GaN layer in N-polar films is smoother than that in Ga-polar films,which suggests different growth modes of GaN.This observation explains the encountered difference in screw and edge TD density.A model is proposed to explain this phenomenon. 相似文献
8.
Groove-type channel enhancement-mode Al GaN/GaN MIS HEMT with combined polar and nonpolar AlGaN/GaN heterostructures 下载免费PDF全文
A novel groove-type channel enhancement-mode AlGaN/GaN MIS high electron mobility transistor(GTCE-HEMT)with a combined polar and nonpolar AlGaN/GaN heterostucture is presented. The device simulation shows a threshold voltage of 1.24 V, peak transconductance of 182 m S/mm, and subthreshold slope of 85 m V/dec, which are obtained by adjusting the device parameters. Interestingly, it is possible to control the threshold voltage accurately without precisely controlling the etching depth in fabrication by adopting this structure. Besides, the breakdown voltage(VB) is significantly increased by 78% in comparison with the value of the conventional MIS-HEMT. Moreover, the fabrication process of the novel device is entirely compatible with that of the conventional depletion-mode(D-mode) polar AlGaN/GaN HEMT. It presents a promising way to realize the switch application and the E/D-mode logic circuits. 相似文献
9.
Low specific on-resistance GaN-based vertical heterostructure field effect transistors with nonuniform doping superjunctions 下载免费PDF全文
A novel Ga N-based vertical heterostructure field effect transistor(HFET) with nonuniform doping superjunctions(non-SJ HFET) is proposed and studied by Silvaco-ATLAS,for minimizing the specific on-resistance(R_(on)A) at no expense of breakdown voltage(BV).The feature of non-SJ HFET lies in the nonuniform doping concentration from top to bottom in the n-and p-pillars,which is different from that of the conventional Ga N-based vertical HFET with uniform doping superjunctions(un-SJ HFET).A physically intrinsic mechanism for the nonuniform doping superjunction(non-SJ) to further reduce R_(on)A at no expense of BV is investigated and revealed in detail.The design,related to the structure parameters of non-SJ,is optimized to minimize the R_(on)A on the basis of the same BV as that of un-SJ HFET.Optimized simulation results show that the reduction in R_(on)A depends on the doping concentrations and thickness values of the light and heavy doping parts in non-SJ.The maximum reduction of more than 51% in R_(on)A could be achieved with a BV of 1890 V.These results could demonstrate the superiority of non-SJ HFET in minimizing R_(on)A and provide a useful reference for further developing the Ga N-based vertical HFETs. 相似文献
10.
Luminescence of a GaN grain with a nonpolar and semipolar plane in relation to microstructural characterization 下载免费PDF全文
We report on the growth of the high-quality GaN grain on a r-plane sapphire substrate by using a self-organized SiN interlayer as a selective growth mask.Transmission electron microscopy,scanning electron microscopy,and Raman spectroscopy are used to reveal the effect of SiN on the overgrown a-plane GaN growth.The SiN layer effectively terminates the propagation of the threading dislocation and basal plane stacking faults during a-plane GaN regrowth through the interlayer,resulting in the window region shrinking from a rectangle to a "black hole".Furthermore,strong yellow luminescence(YL) in the nonpolar plane and very weak YL in the semipolar plane on the GaN grain is revealed by cathodoluminescence,suggesting that C-involved defects are responsible for the YL. 相似文献