Ultralow wear of gallium nitride

Here, we reveal a remarkable (and surprising) physical property of GaN: it is extremely wear resistant. In fact, we measured the wear rate of GaN is approaching wear rates reported for diamond. Not only does GaN have an ultralow wear rate but also there are quite a few experimental factors that control the magnitude of its wear rate, further contributing to the rich and complex physics of wear of GaN. Here, we discovered several primary controlling factors that will affect the wear rate of III-Nitride materials: crystallographic orientation, sliding environment, and coating composition (GaN, InN and InGaN). Sliding in the ⟨12¯10⟩ is significantly lower wear than ⟨11¯00⟩. Wear increases by 2 orders of magnitude with increasing humidity (from ∼0% to 50% RH). III-Nitride coatings are promising as multifunctional material systems for device design and sliding wear applications.