A study was made of the electronic and conduction properties of a single AlN

barrier (thickness from 0.5 to 5nm) embedded in GaN. The electronic structure was

simulated by using a self-consistent Schrödinger–Poisson solver, and verified by

photoluminescence measurements. For 0.5nm and 1nm-thick barriers, it was

possible to identify the photoluminescence line related to recombination from the

first electron confined level at the bottom interface of the barrier to the first hole

confined level at the top interface. The photoluminescence evolution with bias

revealed that most of the applied voltage dropped in the depleted cap layer. Carrier

transport was studied using conductive atomic force microscopy. Reference GaN

layers exhibited a rectifying behaviour between the conductive atomic force

microscopy tip and the GaN surface. In samples with a barrier thickness between 1

and 3nm, blockage by the barrier resulted in a negligible current under direct bias;

except for hot-spots at dislocations (density of about 107/cm2). Finally, in samples

with 5nm-thick AlN barriers, a high-current density appeared at reverse bias, which

was attributed to defects induced by AlN relaxation; as verified by transmission

electron microscopy.

Electronic Transport Through GaN/AlN Single Barriers: Effect of Polarisation and

Dislocations. S.Leconte, L.Gerrer, E.Monroy: Microelectronics Journal, 2009,

40[2], 339-41