Beryllium has long been predicted by first principle theory as the best p-type dopant for GaN and AlN. But experimental validation of these theories has not, until now, borne out the original predictions. A key challenge is the dopant-induced strain leading to Be rejection from substitutional sites in favor of interstitial sites, leading to self-compensation. More flexible growth methods like metal modulated epitaxy (MME) that can operate at substantially lower temperatures than traditional approaches, can more effectively place Be into the proper substitutional lattice sites. MME grown Be-doped AlN shows substantial p-type conductivity with hole concentrations in the range of 2.3 × 10¹⁵–3.1 × 10¹⁸ cm⁻³ at room temperature. While others have achieved sizable carrier concentrations near surfaces via carbon doping or Si implantation, this is the only known demonstration of substantial bulk p-type doping in AlN and is a nearly 1000 times higher carrier concentration than the best previously demonstrated bulk electron concentrations in AlN. The acceptor activation energy is found to be ≈37 meV, ≈8 times lower than predicted in literature but on par with similar results for MME p-type GaN. Preliminary results suggest that the films are highly compensated. A p-AlN:Be/i-GaN:Be/n-GaN:Ge pin diode is demonstrated with substantial rectification.

中文翻译：

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通过铍掺杂实现 AlN 的显着 P 型电导率

长期以来，第一原理理论预测铍是 GaN 和 AlN 的最佳 p 型掺杂剂。但直到现在，这些理论的实验验证还没有证实最初的预测。一个关键的挑战是掺杂剂诱导的应变导致 Be 被置换位点排斥而有利于间隙位点，从而导致自我补偿。更灵活的生长方法，如金属调制外延 (MME)，可以在比传统方法低得多的温度下运行，可以更有效地将 Be 置于适当的替代晶格位点。MME 生长的 Be 掺杂 AlN 显示出显着的 p 型导电性，空穴浓度范围为 2.3 × 10 ¹⁵ –3.1 × 10 ¹⁸  cm ^-3 在室温下。虽然其他人已经通过碳掺杂或 Si 注入在表面附近实现了相当大的载流子浓度，但这是 AlN 中大量 p 型掺杂的唯一已知证明，并且载流子浓度比之前最好的 AlN 中的体电子浓度高出近 1000 倍. 发现受体活化能约为 37 meV，比文献中预测的低 ≈8 倍，但与 MME p 型 GaN 的类似结果相当。初步结果表明，这些薄膜得到了高度补偿。p-AlN:Be/i-GaN:Be/n-GaN:Ge pin 二极管经过大量整流演示。