To prevent or suppress parasitic reactions (polycrystalline GaN deposition on the surface of susceptors) in the bulk GaN growth process, catalytic tungsten carbide (WC) layers are proposed as anti-parasitic-reaction (APR) coatings. An industrially feasible technique for producing APR coatings on a graphite substrate via a wet powder process is developed and the WC layers are confirmed to effectively prevent or suppress polycrystalline GaN deposition on APR-coated practical reactor components during the bulk growth processes of hydride vapor-phase epitaxy and halogen-free vapor-phase epitaxy. The mechanism of the APR function is investigated using X-ray photoelectron spectroscopy. It is found that a surface nitride layer forms on the topmost surface of the WC catalytic layer after annealing in an NH₃ atmosphere. It is supposed that this nitride layer inhibits the adsorption of active nitrogen adsorbates and Ga species on the catalytic WC layers. The deposition of APR coatings on graphite substrates allows the growth of large bulk GaN crystals, which is necessary for low-cost GaN wafers for vertical GaN power devices.

中文翻译：

---

碳化钨层通过湿粉工艺沉积在石墨衬底上，作为GaN生长中反应堆组件的抗寄生反应涂层

为了防止或抑制块状GaN生长过程中的寄生反应（在基座表面沉积多晶GaN），提出了催化碳化钨（WC）层作为抗寄生反应（APR）涂层。开发了一种工业上可行的技术，该技术用于通过湿粉工艺在石墨基底上生产APR涂层，并证实了WC层可以有效防止或抑制氢化物气相的整体生长过程中在APR涂覆的实际反应器组件上沉积多晶GaN。外延和无卤素气相外延。使用X射线光电子能谱研究了APR功能的机理。发现在NH中退火后在WC催化层的最上表面上形成表面氮化物层。_3个气氛。据推测，该氮化物层抑制了活性氮吸附物和Ga物质在催化WC层上的吸附。APR涂层在石墨基板上的沉积可以生长大块的GaN晶体，这对于用于垂直GaN功率器件的低成本GaN晶片而言是必需的。