单晶Ga2O3薄膜的制备及光电性能研究

STUDY ON PREPARATION AND PHOTOELECTRIC PROPERTIES OF SINGLECRYSTLE Ga2O3 THIN FILMS

王祺祚

11930055

硕士

材料工程

陈朗

2021-05-18

2021-06-11

南方科技大学

深圳

新型第三代半导体氧化镓(Ga2O3)是一种新兴的光学禁带宽度高达4.9 eV的半导体材料，性能优异，在深紫外区域的透明度达到80%以上。它可以替代其他透明导电氧化物在紫外或深紫外光电探测领域发挥重要作用。其中β-Ga2O3是最稳定的晶相，有着稳定性高、耐高温和击穿电压大等优点。众多优点使得人们对于β相的研究较为广泛，其制备手段丰富且衬底选择众多。 本文采用激光脉冲沉积设备(PLD)制备单晶β-Ga2O3薄膜，550 ℃沉积温度以上制得的为单晶薄膜并且随着温度提高薄膜的晶体质量也提高。随着氧气分压增大薄膜三维生长岛尺寸逐渐减小，表面也越来越平整。550 ℃沉积温度以上的薄膜均表现出了良好的紫外透过性，在可见光范围内的透过率均在95%以上，此温度上适当升温可使吸收边蓝移。空气和氮气两种氛围下高温退火后的样品衍射峰的相位均向大角度方向偏移，样品在氮气氛围偏移速度相对值均大于空气氛围中的样品，紫外吸收边也随退火温度升高逐渐蓝移，光学禁带宽度最大可达5.13 eV。 在此基础上制备MSM型紫外光电探测器。氮气氛围中750 ℃退火后器件的光暗电流比最大可达103，高出未退火样品一个数量级。器件的光电流暗电流、光暗电流比和光响应度随着单晶β-Ga2O3薄膜退火温度的升高而降低，且光电流下降速度远大于暗电流。高温退火使缺陷减少，肖特基势垒高度增大，从而使得光电流、暗电流均降低，而重结晶导致运动的电子受到更强的散射作用从而迁移率降低。未退火的样品相比于高温退火后的样品，光、暗电流及光响应度均最大。并且同一退火温度下氮气氛围中退火器件的光、暗电流高于空气氛围中退火的样品，即薄膜经过高温退火，不论氛围中有无氧组分，电阻都会大大增加。 总的来看，750 ℃退火后器件光暗电流比最大，氧气氛围中退火有助于提高时间响应特性。新型第三代半导体氧化镓(Ga2O3)是一种新兴的光学禁带宽度高达4.9 eV的半导体材料，性能优异，在深紫外区域的透明度达到80%以上。它可以替代其他透明导电氧化物在紫外或深紫外光电探测领域发挥重要作用。其中β-Ga2O3是最稳定的晶相，有着稳定性高、耐高温和击穿电压大等优点。众多优点使得人们对于β相的研究较为广泛，其制备手段丰富且衬底选择众多。 本文采用激光脉冲沉积设备(PLD)制备单晶β-Ga2O3薄膜，550 ℃沉积温度以上制得的为单晶薄膜并且随着温度提高薄膜的晶体质量也提高。随着氧气分压增大薄膜三维生长岛尺寸逐渐减小，表面也越来越平整。550 ℃沉积温度以上的薄膜均表现出了良好的紫外透过性，在可见光范围内的透过率均在95%以上，此温度上适当升温可使吸收边蓝移。空气和氮气两种氛围下高温退火后的样品衍射峰的相位均向大角度方向偏移，样品在氮气氛围偏移速度相对值均大于空气氛围中的样品，紫外吸收边也随退火温度升高逐渐蓝移，光学禁带宽度最大可达5.13 eV。 在此基础上制备MSM型紫外光电探测器。氮气氛围中750 ℃退火后器件的光暗电流比最大可达103，高出未退火样品一个数量级。器件的光电流暗电流、光暗电流比和光响应度随着单晶β-Ga2O3薄膜退火温度的升高而降低，且光电流下降速度远大于暗电流。高温退火使缺陷减少，肖特基势垒高度增大，从而使得光电流、暗电流均降低，而重结晶导致运动的电子受到更强的散射作用从而迁移率降低。未退火的样品相比于高温退火后的样品，光、暗电流及光响应度均最大。并且同一退火温度下氮气氛围中退火器件的光、暗电流高于空气氛围中退火的样品，即薄膜经过高温退火，不论氛围中有无氧组分，电阻都会大大增加。 总的来看，750 ℃退火后器件光暗电流比最大，氧气氛围中退火有助于提高时间响应特性。新型第三代半导体氧化镓(Ga2O3)是一种新兴的光学禁带宽度高达4.9 eV的半导体材料，性能优异，在深紫外区域的透明度达到80%以上。它可以替代其他透明导电氧化物在紫外或深紫外光电探测领域发挥重要作用。其中β-Ga2O3是最稳定的晶相，有着稳定性高、耐高温和击穿电压大等优点。众多优点使得人们对于β相的研究较为广泛，其制备手段丰富且衬底选择众多。 本文采用激光脉冲沉积设备(PLD)制备单晶β-Ga2O3薄膜，550 ℃沉积温度以上制得的为单晶薄膜并且随着温度提高薄膜的晶体质量也提高。随着氧气分压增大薄膜三维生长岛尺寸逐渐减小，表面也越来越平整。550 ℃沉积温度以上的薄膜均表现出了良好的紫外透过性，在可见光范围内的透过率均在95%以上，此温度上适当升温可使吸收边蓝移。空气和氮气两种氛围下高温退火后的样品衍射峰的相位均向大角度方向偏移，样品在氮气氛围偏移速度相对值均大于空气氛围中的样品，紫外吸收边也随退火温度升高逐渐蓝移，光学禁带宽度最大可达5.13 eV。 在此基础上制备MSM型紫外光电探测器。氮气氛围中750 ℃退火后器件的光暗电流比最大可达103，高出未退火样品一个数量级。器件的光电流暗电流、光暗电流比和光响应度随着单晶β-Ga2O3薄膜退火温度的升高而降低，且光电流下降速度远大于暗电流。高温退火使缺陷减少，肖特基势垒高度增大，从而使得光电流、暗电流均降低，而重结晶导致运动的电子受到更强的散射作用从而迁移率降低。未退火的样品相比于高温退火后的样品，光、暗电流及光响应度均最大。并且同一退火温度下氮气氛围中退火器件的光、暗电流高于空气氛围中退火的样品，即薄膜经过高温退火，不论氛围中有无氧组分，电阻都会大大增加。 总的来看，750 ℃退火后器件光暗电流比最大，氧气氛围中退火有助于提高时间响应特性。

New third-generation semiconductor gallium oxide (Ga2O3) is an emerging semiconductor material with an optical forbidden band width of up to 4.9 eV. It has excellent performance and has a transparency of more than 80% in the deep ultraviolet region. It can replace other transparent conductive oxides in the field of ultraviolet or deep ultraviolet photodetection. Among them, β-Ga2O3 is the most stable crystal phase, which has the advantages of high stability, high temperature resistance and high breakdown voltage. Numerous advantages make people more extensive research on β- Ga2O3, with abundant preparation methods and numerous substrate choices. In this thesis, laser pulse deposition equipment (PLD) is used to prepare single crystal β-Ga2O3 films. The single crystal films are prepared at a deposition temperature above 550 ℃, and the crystal quality of the films increases as the temperature increases. As the oxygen partial pressure increases, the size of the three-dimensional growth island of the film gradually decreases, and the surface becomes more and more flat. The films above the deposition temperature of 550 °C all show good UV transmittance, and the transmittance in the visible light range is above 95%. A proper increase in this temperature can make the absorption edge blue shift. The phases of the diffraction peaks of the samples after high-temperature annealing in both air and nitrogen atmospheres are shifted to a large angle direction. The relative values of the shift speeds of the samples in the nitrogen atmosphere are greater than those in the air atmosphere, and the UV absorption edge also increases with the annealing temperature. With a gradual blue shift, the maximum optical band gap can reach 5.13 eV. On this basis, an MSM (metal-semiconductor-metal) type ultraviolet photodetector was prepared. The photo-dark current ratio of the device after annealing at 750 °C in a nitrogen atmosphere can reach a maximum of 103, which is an order of magnitude higher than that of the unannealed sample. The photocurrent dark current, photodark current ratio and photoresponse of the device decrease with the increase of the annealing temperature of single crystal β-Ga2O3 film, and the photocurrent decline rate is much faster than the dark current. High-temperature annealing reduces defects and increases the height of the Schottky barrier, thereby reducing both the photocurrent and dark current, and recrystallization causes the moving electrons to undergo stronger scattering and reduce the mobility. Compared with the sample after high temperature annealing, the unannealed sample has the largest light, dark current and light responsivity. The light and dark current of the annealed device in the nitrogen atmosphere at the same annealing temperature is higher than that of the sample annealed in the air atmosphere. That is, after the films are annealed at a high temperature, the resistance will greatly increase regardless of the presence of oxygen-free components in the atmosphere. In general, the light-dark current ratio of the device is the largest after annealing at 750 °C, and annealing in an oxygen atmosphere helps to improve the time response characteristics.

β-Ga2O3 PLD 单晶 紫外光电探测 退火

β-Ga2O3 PLD single crystal ultraviolet photodetection annealing

中文

独立培养

南方科技大学

王祺祚. 单晶Ga2O3薄膜的制备及光电性能研究[D]. 深圳. 南方科技大学,2021.