Ultrathin GaN Crystal Realized Through Nitrogen Substitution of Layered GaS
Ultrathin GaN Crystal Realized Through Nitrogen Substitution of Layered GaS
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DOI：
10.1007/s11664-023-10670-w
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发表时间：
2023-09
影响因子：
2.1
通讯作者：
Jun Cao;Tianshu Li;Hongze Gao;Xin Cong;Miao‐Ling Lin;Nicholas Russo;Weijun Luo;Siyuan Ding;Zifan Wang;Kevin E. Smith;Ping-Heng Tan;Qiong Ma;X. Ling
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文献类型：
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作者：
Jun Cao;Tianshu Li;Hongze Gao;Xin Cong;Miao‐Ling Lin;Nicholas Russo;Weijun Luo;Siyuan Ding;Zifan Wang;Kevin E. Smith;Ping-Heng Tan;Qiong Ma;X. Ling
GaN已被证明是一种重要的宽带隙半导体在许多应用中，特别是在光电子和高功率电子。二维（2D）GaN与体材料相比具有更高的带隙，不仅增强了现有的功能，而且为紧凑型电子产品开辟了新的可能性。尽管最近已经开发了几种方法来合成2D GaN，但是它们的实际应用受到苛刻的生长条件（例如，高温和超真空）或由于晶界而导致的不令人满意的性能。在这里，我们报告了在相对较低的温度（590°C）下通过层状GaS薄片的原位原子取代实现几纳米厚的GaN晶体。通过对不同层数的GaS进行原子替代反应，获得了厚度从50 nm到0.9 nm（~2个原子层）可调的GaN。所获得的GaN薄片保留了从GaS薄片继承的形态，并通过透射电子显微镜（TEM）表征显示出高结晶度，而GaN的厚度从原子力显微镜表征减小到相应GaS薄片的约72%。随时间变化的机制研究揭示了水平和垂直转换路径，与Ga 2S 3作为中间。光致发光（PL）光谱测量结果表明，2D GaN的带边PL是蓝移相比，体GaN，这表明，随着厚度的减小，带隙增加。这项研究提供了一个很有前途的方法，获得可调厚度的高结晶度GaN，利用最小的热预算。这一突破为未来基础物理和潜在器件应用的研究奠定了坚实的基础。
GaN has been demonstrated as an important wide-bandgap semiconductor in many applications, especially in optoelectronic and high-power electronics. Two-dimensional (2D) GaN, with increased bandgap compared to the bulk counterpart, not only amplifies existing functionalities but also opens up fresh possibilities for compact electronics. Although several methods have recently been developed to synthesize 2D GaN, their practical application is hampered by either harsh growth conditions (e.g., high temperature and ultrahigh vacuum) or unsatisfactory performance due to grain boundaries. Here, we report the realization of few-nanometer-thick GaN crystals via in situ atomic substitution of layered GaS flakes at a relatively low temperature (590°C). GaN with tunable thickness from 50 nm down to 0.9 nm (~2 atomic layers) is achieved by applying the atomic substitution reaction to GaS with different numbers of layers. The obtained ultrathin GaN flakes retain the morphology inherited from the GaS flakes and show high crystallinity by transmission electron microscopy (TEM) characterization, while the thickness of GaN decreases to about 72% of the corresponding GaS flakes from the atomic force microscopy characterization. A time-dependent mechanism study reveals both horizontal and vertical conversion paths, with Ga2S3as intermediate. Photoluminescence (PL) spectroscopy measurements show that the band edge PL of 2D ultrathin GaN is blue-shifted as compared with bulk GaN, suggesting that the bandgap increases with the decrease in thickness. This study provides a promising method for obtaining ultrathin, high-crystallinity GaN with tunable thicknesses, utilizing a minimal thermal budget. This breakthrough lays a solid foundation for future investigations into fundamental physics and potential device applications.