Improved p-type conductivity in Al-rich AlGaN using multidimensional Mg-doped superlattices.
Improved p-type conductivity in Al-rich AlGaN using multidimensional Mg-doped superlattices.
复制标题
使用多维镁掺杂超晶格改善富铝 AlGaN 中的 p 型电导率
DOI：
10.1038/srep21897
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发表时间：
2016-02-24
影响因子：
4.6
通讯作者：
Kang JY
中科院分区：
文献类型：
--
作者：
Zheng TC;Lin W;Liu R;Cai DJ;Li JC;Li SP;Kang JY
针对传统掺镁AlGaN超晶格存在的空穴势垒较大的问题，提出了一种新型的多维掺镁超晶格来提高垂直空穴电导。在第一性原理理论框架下的电子结构计算表明，费米能级附近价带的态密度(DOS)沿c轴的离域程度高于传统SL，势垒显著降低。在多维SL势垒中，空穴浓度大大提高。部分电荷和分解的DOS的详细比较表明，垂直电导的改善可以归因于Mg和N之间更强的PZ杂化。在理论分析的基础上，采用金属有机气相外延方法生长了高电导的p型多维Al0.63Ga0.37N/Al0.51Ga0.49N SLS。在室温下，空穴浓度可达3.5×10 18 cm−3，而相应的电阻率降至0.7Ωcm，其电导率是常规激光烧结的数十倍。在100K温度下仍能保持较高的空穴浓度。富铝结构材料的高p型电导率是未来设计优良的AlGaN基深紫外光器件的重要一步。
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 × 1018 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.