摘要
P-N结型耗尽沟道的电流输运取决于沟道中的势垒高度,本文构建了沟道势垒模型,基于器件物理分析给出了势垒高度的解析表达式.该模型对沟道内和沟道外耗尽区的边界条件做了合理的假设和分析,通过求解泊松方程获得上述两个区域的电势分布,将这两个区域的电势分布综合起来推导出了势垒高度的解析表达式.该表达式较为完整地反映了势垒高度与器件材料参数、结构参数及外加偏压的关系.将解析模型与数值模拟结果做了比较,两者吻合很好.该模型的构建对于分析具有P-N结型耗尽沟道的半导体器件有重要意义.
P-N junction plays an important role in some semiconductor devices, such as bipolar junction transistor （BJT）, metal- insulator-semiconductor field-effect transistor （MISFET） and junction field-effect transistor （JFET）. However, the role of P-N junction in static induction device （SID） is different from other devices. SID is the typical example of semiconductor devices with depleted channel formed by two P-N junctions. Based on that, potential barrier has been formed in the channel, which is different from usual potential barrier in other semiconductor devices. The potential barrier controls electron movements in the parallel direction not in the vertical direction. In other words, the channel current is controlled by the potential barrier height, which is dependent on applied voltages. As a kind of junction devices, SID has been widely used in acoustic frequency, high frequency and microwave fields. Compared with other semiconductor devices, SID features high switching speed, high power, high pressure resistance, and strong anti-radiation which has been considered to be a promising power semiconductor device. The key principle of SID is that potential barrier height is dependent on applied voltages. As a result of that, the potential barrier model of SID has been proposed by Bulucea, but it doesn＇t provide the clear analytical expression of potential barrier height with the device structure and applied voltages. Taking into account the defect existed in present potential barrier model of SID, a model of potential barrier in channel based on static induction transistor （SIT） was proposed. SIT as a typical example of SID is a type of power semiconductor device with vacuum-triode-like characteristics. The analytical expression of potential barrier height was deduced based on the analysis of device physics. Moreover, based on the assumed boundary conditions in the channel region and the depleted region bellow the channel region, the analytical expressions of barrier height was calculated by solving the simultaneous electrical potential distribution equations which were obtained by solving the Poison＇s equation. The three-dimensional diagram of electrical potential distribution is obtained and it looks like a saddle. The model reflects the interdependency between the potential barrier and the material parameters, structure parameters and biases conditions. Gate-control efficiency of devices is dependent on channel length and channel width and drain-control efficiency is closely related to channel width and epitaxial impurity density. From the analytical expressions of barrier height, the voltage amplification factor can be improved by reducing drain-control efficiency and increasing gate-control efficiency. The two conditions are all dependent on the channel width. In order to verify the analytical expressions of barrier height, the numerical simulation of SIT was made at different conditions. Considering gate voltages, drain voltages, doping concentration in the epitaxial layer, channel length and channel width, the calculated potential barrier height based on the model is in good agreement with the numerical simulation results. The proposed model of potential barrier can be applied to the theoretical analysis of the I-V characteristics and structure characteristics of SID. Building accurate analytical model of potential barrier height can reduce manufacturing costs of semiconductor devices with depleted channel formed by P-N junction and improve device performance.
作者
肖彤
乔坚栗
陈健
杨建红
XIAO Tong QIAO JianLi CHEN Jian YANG JianHong(Institute of Microelectronics, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, Chin)
出处
《科学通报》
EI
CAS
CSCD
北大核心
2017年第28期3392-3399,共8页
Chinese Science Bulletin
关键词
P—N结
耗尽沟道
势垒模型
泊松方程
解析表达式
P-N junction, the depletion channel, potential barrier model, the Poison＇s equation, analytical expressions
