Zheng T C, Lin W, Liu R, Cai D J, Li J C, Li S P, Kang J Y
Department of Physics, OSED, Fujian Provincial Key Laboratory of Semiconductor Materials and Applications, Xiamen University, Xiamen, 361005, China.
SIMS Lab, Office of the Deputy Vice Chancellor and Vice President, Research and Development, Western Sydney University, Locked Bag 1797 Penrith NSW 2751.
Sci Rep. 2016 Feb 24;6:21897. doi: 10.1038/srep21897.
A novel multidimensional Mg-doped superlattice (SL) is proposed to enhance vertical hole conductivity in conventional Mg-doped AlGaN SL which generally suffers from large potential barrier for holes. Electronic structure calculations within the first-principle theoretical framework indicate that the densities of states (DOS) of the valence band nearby the Fermi level are more delocalized along the c-axis than that in conventional SL, and the potential barrier significantly decreases. Hole concentration is greatly enhanced in the barrier of multidimensional SL. Detailed comparisons of partial charges and decomposed DOS reveal that the improvement of vertical conductance may be ascribed to the stronger pz hybridization between Mg and N. Based on the theoretical analysis, highly conductive p-type multidimensional Al0.63Ga0.37N/Al0.51Ga0.49N SLs are grown with identified steps via metalorganic vapor-phase epitaxy. The hole concentration reaches up to 3.5 × 10(18) cm(-3), while the corresponding resistivity reduces to 0.7 Ω cm at room temperature, which is tens times improvement in conductivity compared with that of conventional SLs. High hole concentration can be maintained even at 100 K. High p-type conductivity in Al-rich structural material is an important step for the future design of superior AlGaN-based deep ultraviolet devices.
提出了一种新型的多维掺镁超晶格（SL），以增强传统掺镁AlGaN超晶格中的垂直空穴导电性，传统掺镁AlGaN超晶格通常存在较大的空穴势垒。第一性原理理论框架内的电子结构计算表明，费米能级附近价带的态密度（DOS）沿c轴比传统超晶格更离域，且势垒显著降低。多维超晶格的势垒中空穴浓度大大提高。对部分电荷和分解态密度的详细比较表明，垂直电导率的提高可能归因于Mg和N之间更强的pz杂化。基于理论分析，通过金属有机气相外延以确定的步骤生长出了高导电p型多维Al0.63Ga0.37N/Al0.51Ga0.49N超晶格。空穴浓度在室温下达到3.5×10(18) cm(-3)，而相应的电阻率降至0.7 Ω cm，与传统超晶格相比，电导率提高了数十倍。即使在100 K时也能保持高空穴浓度。富铝结构材料中的高p型导电性是未来设计优质AlGaN基深紫外器件的重要一步。
