热激光外延法在蓝宝石上生长超导TiN及其界面工程
Growth and Interface Engineering of Superconducting TiN on Sapphire by Thermal-Laser Epitaxy
- Cornell University（康奈尔大学）
- epiray
- Kavli Institute at Cornell for Nanoscale Science（康奈尔纳米科学卡弗里研究所）
- Leibniz-Institut für Kristallzüchtung（莱布尼茨晶体生长研究所）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究采用热激光外延法在蓝宝石上生长TiN，通过低温种子层缓解界面空洞，实现了5.8 K超导转变温度和1.19微欧姆厘米的低电阻率。
AI中文摘要：
热激光外延（TLE）扩展了传统分子束外延可达到的压力、温度和生长速率范围，实现了原位激光退火、高纯度缓冲层生长以及难熔元素的高效蒸发。这些能力使TLE成为制备低损耗超导谐振器和约瑟夫森结异质结构的有前景平台。在此，我们研究了在蓝宝石上通过TLE生长TiN的过程，并观察到随着生长温度升高至1150°C，输运性能得到改善。不幸的是，我们观察到，获得最佳TiN性能所需的高氨气压和升高的衬底温度促进了蓝宝石表面的反应，导致TiN-衬底界面处出现空洞。这些缺陷增加了界面表面积，引入了悬挂键，并可能损害隧道势垒异质结构。我们通过在850°C下生长的初始TiN种子层来缓解这种退化。使用种子层后，我们实现了5.8 K的超导转变温度、12.2的残余电阻率比以及10 K时1.19微欧姆厘米的电阻率，据我们所知，这是蓝宝石上生长的TiN所报道的最低值。
英文摘要：
Thermal-laser epitaxy (TLE) extends the accessible pressure, temperature, and growth-rate regimes of conventional molecular-beam epitaxy, enabling in situ laser annealing, high-purity buffer-layer growth, and efficient evaporation of refractory elements. These capabilities make TLE a promising platform for engineering low-loss superconducting resonators and Josephson-junction heterostructures. Here, we study the TLE growth of TiN on sapphire and observe improved transport properties with increasing growth temperature up to 1150 C. Unfortunately, we observe that the high ammonia pressure and elevated substrate temperatures required for optimal TiN properties promote reactions at the sapphire surface, resulting in voids at the TiN-substrate interface. These defects increase interfacial surface area, introduce dangling bonds, and could compromise tunnel-barrier heterostructures. We mitigate this degradation using an initial TiN seed layer grown at 850 C. With the seed layer, we achieve a superconducting transition temperature of 5.8 K, a residual resistivity ratio of 12.2, and a resistivity of 1.19 micro-ohm cm at 10 K, which, to our knowledge, is the lowest reported for TiN grown on sapphire.
