增强型双异质结器件特性研究

发布时间：2018-05-21 00:35

本文选题：氮化镓 + 增强型　；参考：《西安电子科技大学》2015年硕士论文

【摘要】：氮化镓基器件由于出色的性能,被学术界和工业界广泛的研究。增强型氮化镓器件在开关和数字电路领域也因具有较大的应用前景而被大量研究。背势垒结构能够提高二维电子气的限域性,氟处理是一种常用的实现增强型技术,然而国内外很少学者研究氟处理背势垒结构器件,因此氟处理和背势垒相结合实现增强型器件具有非常好的研究价值。本文从理论模拟和实验制作上研究了低损伤的增强型双异质结器件,研究内容包括以下几个方面:(1)通过模拟仿真,得到了结合氟注入的三种不同GaN沟道厚度双异质结器件(15nm,30nm,60nm),其阈值电压均大于0V。本文首先模拟仿真了常规单异质结器件和双异质结器件特性,发现双异质结器件具有较小的二维电子气浓度。仿真不同GaN沟道层厚度的双异质结器件,发现阈值电压随着沟道层的厚度的增加而越来越负,跨导随着沟道层的厚度的增加而越来越大。仿真了常规氟功率和较低氟功率分别处理单异质结和双异质结器件,采用较低氟处理功率对三种不同GaN沟道厚度的双异质结器件进行处理,均得到了阈值电压大于0V的效果。(2)通过实验,成功制作了三种不同GaN沟道的增强型双异质结器件(14nm,28nm,60nm),且退火后保持较大的阈值电压。我们使用135W氟处理功率对三种不同GaN沟道的增强型双异质结器件(14nm,28nm,60nm)进行处理,退火前它们的阈值电压能达到1.1V、0.8V和0.3V,它们的峰值跨导分别达到110mS/mm、146mS/mm、198mS/mm。为了进一步提高器件的性能,我们对其进行退火处理。由于135W氟处理功率对器件的损伤较小,退火之后两种不同GaN沟道的增强型双异质结器件(14nm、28nm)的阈值电压分别达到0.7V、0.4V,它们的峰值跨导分别达到161mS/mm、198mS/mm。在肖特基特性方面,我们发现,在隧穿机制的影响下,栅反向电流随着GaN沟道层厚度增加而增加。(3)通过实验,分析了双异质结器件的变温特性。我们对器件进行从20度到270度的在片变温测试。在直流特性方面,当温度从20度上升到70度时,器件的直流特性性能非常稳定,当温度继续升高时,由于氟离子的移动,阈值电压逐渐负向移动;在肖特基特性方面,在不同的温度区间由不同的电流输运机制控制。对于反向肖特基电流,在隧穿机制和碰撞机制的共同作用下,肖特基反向电流先增大后减小。对于正向肖特基电流,在隧穿机制和热电子发射机制共同作用下,肖特基正向电流亦是先增大后减小;在DIBL特性方面,常温下14nm GaN沟道双异质结器件具有非常好的限域性,其DIBL特性值仅为16mV/V,但随着温度升高,其DIBL特性不稳定,限域性变差,常温下28nm GaN沟道双异质结器件限域性也较好,其DIBL特性值为30mV/V,随着温度升高,DIBL特性较为稳定,限域性依然保持较好。
[Abstract]:Gallium nitride based devices have been widely studied in academia and industry due to their excellent performance. Enhanced gallium nitride devices have also been widely studied in the field of switches and digital circuits because of their great application prospects. The back barrier structure can improve the localization of two-dimensional electron gas. Fluorine treatment is a commonly used enhancement technique. However, few scholars at home and abroad have studied the device. Therefore, it is of great value to combine fluorine treatment with back barrier to realize enhanced devices. In this paper, low-damage enhanced dual-heterojunction devices are studied in terms of theoretical simulation and experimental fabrication. The research contents include the following aspects: 1. Three kinds of GaN double heterojunction devices with different channel thickness have been obtained for fluorine injection. The threshold voltages of these devices are all greater than 0 V. In this paper, the characteristics of conventional single-heterojunction devices and double-heterojunction devices are simulated, and it is found that the dual-heterojunction devices have a small two-dimensional electron gas concentration. By simulating the double heterojunction devices with different GaN channel layer thickness, it is found that the threshold voltage becomes more and more negative with the increase of channel layer thickness, and the transconductance increases with the increase of channel layer thickness. The conventional fluorine power and the lower fluorine power are used to deal with single heterojunction and double heterojunction devices respectively. Three kinds of GaN channel thickness double heterojunction devices are processed by using lower fluorine processing power. Through experiments, three kinds of enhanced double heterojunction devices with different GaN channels have been successfully fabricated, and the threshold voltage has been maintained after annealing. We use 135W fluorine treatment power to deal with three kinds of enhanced dual-heterojunction devices with different GaN channels. Before annealing, their threshold voltages can reach 1.1 V ~ (0.8) V and 0.3 V, and their peak transconductance reaches 110 Ms / mm ~ (-1) ~ 146mS / mm ~ (-1) m ~ (-1) / m ~ (-1) respectively. In order to further improve the performance of the device, we annealed it. Because the 135W fluorine treatment power has less damage to the device, the threshold voltage of the two kinds of GaN channel enhanced dual-heterostructure devices is 0.7V 0.40V, and their peak transconductance is 161mSr / mm ~ 198mS 路mmm. respectively after annealing, the threshold voltages of the two kinds of GaN channels are up to 0.7 V ~ (-1) V ~ (-1) ~ (-1) V ~ (-1) ~ (-1) V ~ (-1) 路m ~ (-1), respectively. In terms of Schottky characteristics, we find that under the influence of tunneling mechanism, the gate reverse current increases with the thickness of GaN channel layer. We measure the temperature of the device from 20 degrees to 270 degrees in situ. In terms of DC characteristics, when the temperature rises from 20 degrees to 70 degrees, the DC performance of the device is very stable. When the temperature continues to rise, the threshold voltage gradually moves negatively due to the movement of fluorine ions; in terms of Schottky characteristics, It is controlled by different current transport mechanism in different temperature range. For reverse Schottky current, the Schottky reverse current increases first and then decreases under the combined action of tunneling mechanism and collision mechanism. For the forward Schottky current, the Schottky forward current increases first and then decreases under the combined action of tunneling mechanism and thermionic emission mechanism. In terms of DIBL characteristics, the 14nm GaN channel double heterojunction device has a very good limiting property at room temperature. The DIBL characteristic value is only 16mV / V, but with the increase of temperature, the DIBL characteristic is unstable, the limited region becomes worse, and the 28nm GaN channel dual-heterojunction device has a better localized value at room temperature, and its DIBL characteristic value is 30mV / V, and the DIBL characteristic is stable with the increase of temperature. The limitation is still good.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN386

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