In recent years, Gallium Nitride (GaN) has been established as a material of choice for high power switching, high power RF and lighting applications. In c-direction, depending on the surface termination III-nitrides have either a group III element (Al, In, Ga) polarity or a N-polarity. Currently, commercially available GaN-based electronic and optoelectronic devices are fabricated predominantly on Ga-polar GaN. However, N-polar nitride heterostructures due its intrinsic material properties, including opposite polarization field and more chemically reactive surface, can provide benefits for these applications. In this article, some of important electronic and optical properties of N-polar (In, Ga, Al)N thin films and heterostructures have been reviewed. Different techniques that have been used for the epitaxial growth of these materials including tri-halide vapor phase epitaxy (THVPE), metalorganic chemical vapor deposition (MOCVD), and plasma-assisted molecular beam epitaxy (PAMBE) have been discussed. Finally, some of important process technologies that have been developed for fabrication of N-polar GaN high electron mobility transistors are presented.

近年来，氮化镓 (GaN) 已成为高功率开关、高功率射频和照明应用的首选材料。在 c 方向上，根据表面终止，III 族氮化物具有 III 族元素（Al、In、Ga）极性或 N 极性。目前，市售的基于 GaN 的电子和光电器件主要是在 Ga-polar GaN 上制造的。然而，N 极性氮化物异质结构由于其固有的材料特性，包括相反的极化场和更具化学反应性的表面，可以为这些应用提供好处。在本文中，回顾了 N 极（In、Ga、Al）N 薄膜和异质结构的一些重要电子和光学特性。已经讨论了用于这些材料外延生长的不同技术，包括三卤化物气相外延 (THVPE)、金属有机化学气相沉积 (MOCVD) 和等离子体辅助分子束外延 (PAMBE)。最后，介绍了为制造 N 极 GaN 高电子迁移率晶体管而开发的一些重要工艺技术。