Materials design and development of new spinel silicon nitrides

具有尖晶石结构的立方氮化硅是由德国的一个小组在1999年发现的。通过第一性原理计算，我们发现立方氮化硅的直接带隙为3.5eV，这与传统的六方结构氮化硅的间接带隙和更宽的带隙有明显的不同。本论文通过第一性原理计算和高压实验相结合的方法，为尖晶石型氮化物的材料设计和开发提供了新的思路，并通过系统的理论计算，找到了适合于n型和p型半导体氮化物的掺杂剂。本文系统地进行了Si-Al-Mg-O-N系高压相的冲击波合成实验。

Cubic silicon nitride having spinel structure was discovered by a German group in 1999. We have found by first principles calculations that the cubic silicon nitride has a direct band gap of 3.5eV, which is markedly different from the indirect and wider band gaps in conventional silicon nitrides with hexagonal structures. It was also predicted to possess higher hardness than hexagonal crystals.In the present study, we have combined efforts of first principles calculations and high pressure experiments to have new ideas for materials design and development of new spinel nitrides.We have found good dopants for n and p-type semiconducting nitrides through systematic theoretical calculations. Shock wave syntheses experiments were systematically made to explore the high pressure phases within Si-Al-Mg-O-N systems.