146 research outputs found
Demonstration of Forward Inter-band Tunneling in GaN by Polarization Engineering
We report on the design, fabrication, and characterization of GaN interband
tunnel junction showing forward tunneling characteristics. We have achieved
very high forward tunneling currents (153 mA/cm2 at 10 mV, and 17.7 A/cm2 peak
current) in polarization-engineered GaN/InGaN/GaN heterojunction diodes grown
by plasma assisted molecular beam epitaxy. We also report the observation of
repeatable negative differential resistance in interband III-Nitride tunnel
junctions, with peak-valley current ratio (PVCR) of 4 at room temperature. The
forward current density achieved in this work meets the typical current drive
requirements of a multi-junction solar cell.Comment: 3 figure
Electrical Properties of Atomic Layer Deposited Aluminum Oxide on Gallium Nitride
We report on our investigation of the electrical properties of
metal/Al2O3/GaN metal-insulator-semiconductor (MIS) capacitors. We determined
the conduction band offset and interface charge density of the alumina/GaN
interface by analyzing capacitance-voltage characteristics of atomic layer
deposited Al2O3 films on GaN substrates. The conduction band offset at the
Al2O3/GaN interface was calculated to be 2.13 eV, in agreement with theoretical
predications. A non-zero field of 0.93 MV/cm in the oxide under flat-band
conditions in the GaN was inferred, which we attribute to a fixed net positive
charge density of magnitude 4.60x1012 cm-2 at the Al2O3/GaN interface. We
provide hypotheses to explain the origin of this charge by analyzing the energy
band line-up.Comment: 8 pages, 4 figures, Applied Physics Letter
First principles calculation of polarization induced interfacial charges in GaN/AlN heterostructures
We propose a new method to calculate polarization induced interfacial charges
in semiconductor heterostructures using classical electrostatics applied to
real-space band diagrams from first principles calculations and apply it to
GaN/AlN heterostructures with ultrathin AlN layers (4-6 monolayers). We show
that the calculated electric fields and interfacial charges are independent of
the exchange-correlation functionals used (local-density approximation and
hybrid functionals). We also find the calculated interfacial charge of (6.8 +/-
0.4) x 10^13 cm-2 to be in excellent agreement with experiments and the value
of 6.58 x 10^13 cm-2 calculated from bulk polarization constants, validating
the use of bulk constants even for very thin films.Comment: 3 pages, 2 figures; submitted to Applied Physics Letter
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