Short‐period AlN/GaN p‐type superlattices: hole transport use in p‐n junctions

Hole transport properties of short‐period Mg‐doped AlN/GaN superlattices are compared with bulk Mg‐doped GaN layers. Due to polarization‐induced reduction in acceptor ionization energy, the superlattice structures are observed to result in a nearly temperatureindependent in‐plane p‐type conductivity as opposed to a 100‐fold decrease in bulk p‐type GaN as temperature drops from 300 K to 100 K. Moreover, significant vertical p‐type conductivity is facilitated by the ultrathin AlN barriers due to possible hole tunneling & miniband formation: p‐n junctions are demonstrated by replacing the p‐type GaN layer by a superlattice. The results indicate the feasibility of enhancement of both vertical and lateral p‐type conductivity in bipolar transistors and deep‐UV optical devices. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)