Simulation of New Solid State Cold Cathode Emitters Using Current Carrying Thin Films

我们分析了两种新型的冷阴极发射体，它们是由夹在重掺杂半导体（或金属材料）和低功函数半金属薄膜之间的薄的宽带隙半导体材料组成的。首先，我们开发了一个集成蒙特卡罗（EMC）模拟器来研究氮化镓铝(AlGaN) /氮化镓(GaN)/六硼化镧（LaB6）冷阴极发射器中的电子传输。我们的模拟重点是计算电子发射到真空中的能谱和新型冷阴极的量子效率。然后，使用解析处理，我们表明，在正向偏置操作下，在典型冷阴极的低功函数材料中捕获的电子负责有效地降低半金属膜功函数，导致阴极发射电流大幅增加。由于使用EMC模拟对这种动态功函数移位的研究将非常麻烦，因此我们在这里使用半解析处理进行研究。尽管在Akinwande的冷阴极发射器中可以观察到动态功函数移位，但我们在这里展示了一种新型的冷阴极发射器，该发射器使用硫化镉（CdS）作为宽带隙半导体，硫化镧（LaS）作为半金属薄膜。我们将分析所提出的冷阴极中电流拥挤的重要性，并将确定不同宽度的冷阴极必须运行的直流偏置范围，以尽量减少电流拥挤和自热效应。我们还将研究新型冷阴极中电流自猝灭的可能性，作为所施加的栅极偏压的函数。这种自猝灭将在栅极和阳极之间区域的空间电荷效应的动力学方面进行研究。这些空间电荷效应预计会导致阳极电流中电流振荡的开始。这些电流振荡的周期将作为外加栅极偏置的函数来计算。在这个程序中开发的仿真工具可以很容易地修改，以模拟各种各样的其他设备，包括：高效的蓝色和紫外线发光设备，高能光探测系统，平板显示器和微波真空晶体管等。＊＊＊

9632511 Cahay We analyze two new types of cold cathode emitters which consist of a thin wide bandgap semiconductor material sandwiched between a heavily doped semiconductor (or metallic material) and a low work function semimetallic thin film. First, we develop an Ensemble Monte Carlo (EMC) simulator to study electron transport in a Aluminum Gallium Nitride (AlGaN) / Gallium Nitride (GaN)/ Lanthanum Hexaboride (LaB6) cold cathode emitter recently proposed by Akinwande and coworkers. Our simulations focus on the calculation of the energy spectrum of electrons emitted into vacuum and the quantum efficiency of the new cold cathode. Then, using an analytical treatment, we show that under forward bias operation the electrons captured in the low work function material of a typical cold cathode are responsible for an effective reduction of the semimetallic film work function, leading to a substantial increase of the cathode emitted current. Since the investigation of this Dynamic Work Function Shift would be quite cumbersome using EMC simulations, we investigate it here using a semi-analytical treatment. Even though the dynamic work function shift could be observed in Akinwande's cold cathode emitter, we illustrate it here for a new type of cold cathode emitter using Cadmium Sulfide (CdS) as a wide bandgap semiconductor and Lanthanum Sulfide (LaS) as the semimetallic thin film. We will analyze the importance of current crowding in the proposed cold cathodes and will determine the range of dc bias over which cold cathodes of different width must be operated to minimize current crowding and self-heating effects. We will also study the possibility of current self-quenching in the new cold cathode as a function of the applied gate bias. This self-quenching will be examined in terms of the dynamics of the spacecharge effects in the region between the gate and the anode. These space-charge effects are expected to lead to the onset of current mscillations in the anode current. The period of these current oscillations will be calculated as a function of the applied gate bias. The simulation tools to be developed in this program can be easily modified to model a wide variety of other devices including: efficient blue and ultraviolet light-emitting devices, high-energy photodetection systems, flat panel displays, and microwave vacuum transistors, among others. ***