CAREER: Fundamental Physics and Device Issues of Novel GaAs Thermophotovoltaic Cells

许多民用和军事企业对热光电发电（TPV）表现出浓厚的兴趣，认为它是一种有吸引力、清洁、高效和廉价的替代能源。TPV热源的低功率（约1400℃）使得锑化镓（GaSb）而不是硅成为TPV电池最常用的材料。目前对GaSb TPV电池的研究主要集中在：(1)提高TPV效率；(2)降低生产成本。本文提出了砷化镓（GaAs）作为TPV电池可行材料的首次研究。有两个令人信服的原因。首先，在GaAs衬底上制造TPV电池可以利用现有的GaAs设备进行低成本、高产量、大批量生产，与大型6英寸衬底上的GaAs集成电路（ic）兼容。其次，我们创新的TPV电池可以设计出非常高的效率，因为它们在相同的砷化镓衬底上同时响应近红外（小于1.5微米）和中红外（2-5微米）。本文提出了在GaAs上制造高效TPV电池的三种使能技术：(1)创新设计子带间TPV器件，实现宽带热源的高功率转换效率；(2)新型低温生长（LTG）砷化镓在1.5微米波长（重要的TPV波长）处具有强吸收；(3)高掺杂（10^{20}cm^{-3}）触点的生长和退火，以及串联tpv电池的高掺杂隧道结。这个提议的工作非常适合学术环境，因为它的跨学科性质，强调：理论和实验；吸收、运输和材料的基础研究；以及创新的冠脉光伏电池。其中一项创新是子带间串联TPV （ITTPV）电池的设计，其预计转换效率（35%）远高于现有设备的转换效率（6%）。提出的LTG-GaAs的研究超越了以前的工作，因为它强调了1.5微米处更强吸收的物理和工程。关于高掺杂TPV隧道结和接触的工作强调：建立掺杂限制的物理模型；还有一种新型的热退火，速度比目前最先进的技术快得多（毫秒而不是秒）。PI的教育计划有三个组成部分：(1)新课程开发，(2)指导活动，(3)参与研究研讨会。

TNumerous civilian and military ventures are showing keen interest in the thermo photovoltaic (TPV) generation of electricity as an attractive, clean, efficient, and inexpensive alternative energy. The low power (about 1400 C) of TPV heat sources makes gallium antimonide (GaSb), rather than silicon, the most common material for TPV cells. Research on GaSb TPV cells is currently focused on: (1) increasing the TPV efficiency, and (2) reducing the cost of production. This document proposes the first study of gallium arsenide (GaAs) as a viable material for TPV cells. There are two compelling reasons. First, the manufacture of TPV cells on a GaAs substrate could take advantage of existing GaAs facilities for low-cost, high-yield, large-volume production compatible with GaAs integrated circuits (ICs) on large six-inch substrates. Second, our innovative TPV cells can be designed for exceptionally high efficiency because of theirsimultaneous response, on the same GaAs substrate, to both the near infrared (less than 1.5micron) and the mid-infrared (2-5micron).This proposal develops three enabling technologies for making high efficiency TPV cells on GaAs: (1) innovative design of intersubband TPV devices for high power conversion efficiency of broadband heat sources; (2) novel Low-Temperature Grown (LTG) GaAs designed for strong absorption at the 1.5micron wavelength (an important TPV wavelength); (3) growth and annealing of very highly doped (10^{20}cm^{-3}) contacts, and highly doped tunnel junctions connecting series-TPV cells. This proposed work is ideally suited for an academic environment because of its interdisciplinary nature, emphasizing: both theory and experiment; fundamental studies of absorption, transport, and materials; and innovative TPV cells. One innovation is the proposed design of Intersubband Tandem TPV (ITTPV) cells, which have projected conversion efficiencies (35%) much higher than those (6%) of existing devices. The proposed study of LTG-GaAs goes beyond previous work in that it emphasizes the physics and engineering of a much stronger absorption at 1.5micron. The proposed work on very highly doped TPV tunnel junctions and contacts emphasizes: developing physical models of doping limitations; and a novel thermal anneal much more rapid (milliseconds instead of seconds) than the state-of-the-art capability. PI's educational program has three components: (1) new curriculum development, (2) mentoring activities, and (3) participation in research seminars.