Diamond, a wide bandgap semiconductor, has captivated researchers for decades due to its exceptional properties. While p-type doping has dominated the field, the advent of n-type diamond, doped by nitrogen or phosphorus, has unlocked novel prospects for diverse applications. Nonetheless, the chemical vapor deposition (CVD) of n-type diamond faces substantial hurdles, particularly concerning crystalline quality and dopant concentration control. In this Account, we summarize our progress in developing high quality CVD n-type diamond films. Our research initiates with nitrogen introduction into the CH₄/H₂ CVD plasma for depositing polycrystalline diamond films. The addition of 4% N₂ gas induces the formation of ultra-nanosized diamond grains through CN species, but further increases in nitrogen content result in grain agglomeration into larger sizes. Fixing 3% of N₂ in the CVD plasma, we explore the influence of methane concentration on N-doped nanocrystalline diamond (NCD) films. At a low methane concentration of 1%, faceted diamond grains are formed, while increasing methane to 15% yields nanoneedles encased in nanographitic phases, featuring a low resistivity of 90 Ω·cm. We further investigate P-doped polycrystalline diamond films, where preliminary examinations of P-doped NCD reveal well-defined grain structures but also morphological imperfections and twin boundaries, with a phosphorus incorporation of ≈10¹⁹ cm^–3. Our investigations also cover P-doped (110)-textured polycrystalline CVD diamond films, finding that the phosphorus concentration varies with grain misorientation and that higher phosphine concentrations lead to a more uniform distribution. Additionally, we note that an increase in the [P]/[C] ratio in the CVD plasma of P-doped diamond growths leads to the transformation of NCD to ultra-NCD, reducing residual stress, and affecting film quality. In a complementary investigation, we explore the codoping of NCD films with nitrogen and phosphorus, observing a transition from micron-sized faceted diamond grains to nanosized grains with increasing nitrogen content at a fixed amount of phosphorus concentration in the CVD plasma.

中文翻译：

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n 型化学气相沉积金刚石生长的进展：形态和掺杂剂控制

金刚石是一种宽带隙半导体，由于其卓越的性能，几十年来一直吸引着研究人员。虽然p型掺杂在该领域占据主导地位，但掺杂氮或磷的n型金刚石的出现为各种应用开辟了新的前景。尽管如此， n型金刚石的化学气相沉积（CVD）面临着巨大的障碍，特别是在晶体质量和掺杂剂浓度控制方面。在本报告中，我们总结了我们在开发高质量 CVD n型金刚石薄膜方面取得的进展。我们的研究始于将氮气引入CH ₄ /H ₂ CVD 等离子体以沉积多晶金刚石薄膜。添加4% N ₂气体通过CN物质诱导超纳米金刚石晶粒的形成，但氮含量的进一步增加导致晶粒团聚成更大的尺寸。在CVD等离子体中固定3%的N ₂，我们探讨了甲烷浓度对氮掺杂纳米晶金刚石（NCD）薄膜的影响。在 1% 的低甲烷浓度下，形成多面金刚石颗粒，而将甲烷增加到 15% 时，会产生包裹在纳米石墨相中的纳米针，其电阻率低至 90 Ω·cm。我们进一步研究了 P 掺杂多晶金刚石薄膜，其中 P 掺杂 NCD 的初步检查揭示了明确的晶粒结构，但也显示了形态缺陷和孪晶界，磷掺入量约为 10 ¹⁹ cm ^–3。我们的研究还涵盖了 P 掺杂 (110) 织构的多晶 CVD 金刚石薄膜，发现磷浓度随晶粒取向错误而变化，并且较高的磷化氢浓度导致更均匀的分布。此外，我们注意到，P 掺杂金刚石生长的 CVD 等离子体中 [P]/[C] 比率的增加会导致 NCD 转变为超 NCD，从而减少残余应力并影响薄膜质量。在一项补充研究中，我们探索了 NCD 薄膜与氮和磷的共掺杂，观察到在 CVD 等离子体中磷浓度固定的情况下，随着氮含量的增加，从微米级多面金刚石晶粒到纳米级晶粒的转变。