论文标题
使用原子较薄的Aln/Gan数字合金超级晶格提高Algan的迁移率和功率电子功能数字
Increasing the mobility and power-electronics figure of merit of AlGaN with atomically thin AlN/GaN digital-alloy superlattices
论文作者
论文摘要
随机Algan合金中的合金散射大幅度降低了电子迁移率，因此可以降低功率 - 功率 - 优点图。结果，与GAN相比，Baliga优异数字甚至增加了两倍的增长，需要大于75％的Al组成。但是，除了大约80％的Al组成之外，Algan的捐赠者经历了DX过渡，这使杂质兴奋剂越来越困难。此外，接触电阻随着Al含量的增加而指数增加，并且由于传导带的向上移位，与介电的集成变得困难。众所周知，Aln和Gan的原子较薄的超晶格（也称为数字合金）在适当的生长条件下实验生长。这些化学有序的纳米结构与由于没有合金散射以及与接触金属和介电性更好的整合，因此与它们的随机合金相比，与随机合金相比，它们的优异数字可以显着增强。在这项工作中，我们使用基于密度功能和多体扰动理论的第一原理计算，研究了原子薄/GAN数字合金超级晶格的电子结构和语音限制的电子迁移率。原子薄的超级晶格的频带间隙达到4.8 eV，平面内（平面外）移动性为369（452）cm $^2 $^2 $ v $^{ - 1} $ s $^{ - 1} $。 Using the modified Baliga figure of merit that accounts for the dopant ionization energy, we demonstrate that atomically thin AlN/GaN superlattices with a monolayer sublattice periodicity have the highest modified Baliga figure of merit among several technologically relevant ultra-wide band-gap materials, including random AlGaN, $β$-Ga$_{2}$O$_{3}$, cBN, and 钻石。
Alloy scattering in random AlGaN alloys drastically reduces the electron mobility and therefore the power-electronics figure of merit. As a result, Al compositions greater than 75% are required to obtain even a two-fold increase of the Baliga figure of merit compared to GaN. However, beyond approximately 80% Al composition, donors in AlGaN undergo the DX transition which makes impurity doping increasingly more difficult. Moreover, the contact resistance increases exponentially with increasing Al content, and integration with dielectrics becomes difficult due to the upward shift of the conduction band. Atomically thin superlattices of AlN and GaN, also known as digital alloys, are known to grow experimentally under appropriate growth conditions. These chemically ordered nanostructures could offer significantly enhanced figure of merit compared to their random-alloy counterparts due to the absence of alloy scattering, as well as better integration with contact metals and dielectrics. In this work, we investigate the electronic structure and phonon-limited electron mobility of atomically thin AlN/GaN digital-alloy superlattices using first-principles calculations based on density-functional and many-body perturbation theory. The band gap of the atomically thin superlattices reaches 4.8 eV, and the in-plane (out-of-plane) mobility is 369 (452) cm$^2$ V$^{-1}$ s$^{-1}$. Using the modified Baliga figure of merit that accounts for the dopant ionization energy, we demonstrate that atomically thin AlN/GaN superlattices with a monolayer sublattice periodicity have the highest modified Baliga figure of merit among several technologically relevant ultra-wide band-gap materials, including random AlGaN, $β$-Ga$_{2}$O$_{3}$, cBN, and diamond.
