在宽带隙半导体器件快速发展的同时，作为超宽带隙半导体材料的Ga₂O₃因其独特的优势得到极大的重视。从材料本身的特性来看，Ga₂O₃具有超宽的带隙(4.9 eV)、高的临界击穿电场(8 MV/cm)以及高的巴利加优值(3444)。氧化镓理论上的损耗远低于硅、碳化硅以及氮化镓。同时，大尺寸、高质量的天然衬底可通过熔融生长的方法获得，具有低花费、低导通密度的优点。

目前为止，关于Ga₂O₃基的肖特基势垒二极管、金属氧化物半导体场效应晶体管(MOSFET)和日盲光电探测器等器件的报道很多，在这些器件中，MOSFET成为大功率器件的主流。目前氧化镓 MOSFET 器件的研究多为耗尽型且无法进行P型掺杂，基于此设计了横向增强型的异质结金属氧化物半导体场效应晶体管。主要研究成果如下：

(1)首先在Sentaurus TCAD软件中添加了氧化镓材料的模型参数，主要包括能带、热力学、迁移率、碰撞离化、雪崩击穿等模型。提出了增强型的横向SiC/Ga₂O₃异质结金属氧化物半导体场效应晶体管，充分利用了PN结的开关特性与击穿特性，此次设计实现了0.82 V的开启电压和1817 V的高击穿电压。之后对器件的各部分参数进行了对比分析，研究各部分参数对器件电学性能的影响。通过对比发现SiC的长度、厚度以及掺杂浓度，沟道层的厚度、掺杂浓度，金属功函数等对器件电学特性的影响比较明显；当栅长大于2微米时其对器件转移特性的影响减小；栅源距离和栅漏距离主要影响器件的输出特性；介电常数的增加，会使器件的阈值电压和饱和漏电流都随之增加。

(2)设计了新型增强型(E-mode)的斜面NiO/Ga₂O₃异质结金属氧化物半导体场效应晶体管，实现了0.153 V的开启电压和3069 V的击穿电压，其对应的功率品质因数高达3.602 GW/cm²。相对于普通NiO/Ga₂O₃异质结器件和传统的Ga₂O₃器件而言，加入斜面NiO器件的阈值电压和饱和漏电流都有了明显的提高；综上所述，加入斜面P型掺杂的NiO可以作为提高器件性能的一种思路。

(3)加入非理想效应研究其对器件性能的影响，主要包括陷阱和自热效应两种，其中陷阱研究了固定电荷、界面态（施主和受主）对器件输出特性的影响，自热效应研究了不同环境温度、不同的热阻、不同的衬底厚度以及不同的晶向时的输出特性曲线的变化规律。通过研究发现温度升高会导致器件的饱和漏电流降低。[010]晶向由于具有较高的热导率，能够提升半导体材料中载流子的迁移率，降低散射现象对载流子迁移率的影响。通过对不同热阻的研究发现，该值小于0.005 cm²KW^-1时，其对器件自热效应的影响较小。

With the rapid development of broad band gap semiconductor devices, Ga₂O₃, as an ultra-wide band gap semiconductor material, has received great attention due to its unique advantages. From the characteristics of the material itself, Ga₂O₃ has an ultra-wide band gap (4.9 eV), a high critical breakdown electric field (8 MV/cm), and high Baliga figure of merit (3444). The theoretical loss of gallium oxide is much lower than that of Si, SiC and GaN. At the same time, natural substrates with large size and high quality can be obtained by melt growth, which has the advantages of low cost and low conduction density.

So far, there are many reports on Ga₂O₃-based Schottky barrier diodes, MOSFETs and solar-blind photodetectors. Among these devices, MOSFETs have become the mainstream of high-power devices. At present, most of the research on gallium oxide MOSFET devices is depletion type and cannot be P-doped. Based on this, a laterally enhanced heterojunction metal oxide semiconductor field effect transistor is designed. The main research results are as follows :

(1)Firstly, the model parameters of gallium oxide materials are added in Sentaurus TCAD, including bandgap, thermodynamic, mobility, impact ionization, avalanche and so on. An enhanced lateral SiC/Ga₂O₃ heterojunction metal oxide semiconductor field effect transistor is proposed, which makes full use of the switching characteristic and breakdown characteristic of PN junction. The design achieves an threshold voltage of 0.82 V and a high breakdown voltage of 1817 V. After that, the parameters of each part of the device were compared and analyzed to study the influence of each part of the parameters on the electrical performance of the device. Through comparison, it is found that the length, thickness and doping concentration of SiC, the thickness and doping concentration of channel layer, and the metal work function have obvious influence on the electrical characteristics of the device. When the gate is longer than 2 microns, its influence on the transfer characteristics is reduced. The gate-source distance and gate-drain distance mainly affect the output characteristics of the device. The increase of dielectric constant will increase the threshold voltage and saturation current of the device.

(2)A novel E-mode slope NiO/Ga₂O₃ heterojunction metal oxide semiconductor field effect transistor is designed, which achieves a turn-on voltage of 0.153 V and a breakdown voltage of 3069 V. The corresponding power figure of merit is as high as 3.602 GW/cm².Compared with the common NiO/Ga₂O₃ heterojunction device and the traditional Ga₂O₃ device, the threshold voltage and saturation current of the device with inclined NiO have been significantly improved. In summary, the addition of inclined P-type doped NiO can be used as an idea to improve device performance.

(3) The effects of non-ideal effects on device performance are studied, mainly including the trap and the self-heating effect. The trap studies the influence of fixed charge and interface state (donor and acceptor ) on the output characteristics of the device. The self-heating effect studies the variation of the output characteristic curve of different ambient temperature, different thermal resistance, different substrate thickness and different crystal orientation. It is found that the increase of temperature will lead to the decrease of saturation current of the device. Due to its high thermal conductivity, the [010] crystal orientation can improve the carrier mobility in semiconductor materials and reduce the influence of scattering on carrier mobility. Through the study of different thermal resistance, it is found that when the value is less than 0.005 cm²KW^-1, it has little effect on the self-heating effect of the device.

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