Current transport through AlInN/GaN multilayers used as n‐type cladding layers in edge emitting laser diodes

Abstract

The current transport properties of an n ‐doped, lattice matched AlInN layer with multiple, periodic GaN insertions are reported. Samples with three and seven insertions were grown and mesa structures were etched through the AlInN structures to different depths to determine the voltage contribution from each heterointerface. The quality of the AlInN surface improved with the GaN insertions and with reducing the thickness of the individual AlInN layers from 80 nm to 55 nm. Simulations suggest that the large conduction band discontinuity can lead to high turn on voltages which can be reduced by high levels of doping. Current‐voltage measurements through the full structure show a diode characteristic which is temperature activated. A quasi‐linear current‐voltage characteristic is measured when the current is driven only through the uppermost GaN interlayer with 80 nm thick AlInN layers, indicating current leakage through defects in these layers (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Highly reflective and conductive AlInN/GaN distributed Bragg reflectors realized by Ge-doping

“…Contrary to GaAs-VCSELs with highly conductive arsenide-based DBRs, AlInN/GaN-based DBRs usually exhibit a considerable electrical resistance due to large polarization fields and a significant conduction band offset between GaN and AlInN. 3,[11][12][13][14] In most cases of GaN VCSELs fabrication, intracavity contacts are applied, leading to a higher threshold-current density, lower optical confinement, a lower device performance and increased cost of the device fabrication process. 9,15,16) Doping of the AlInN/GaN DBR layers could solve this problem.…”

Microscopic analysis of interface composition dynamics in m-plane AlInN

“…4,5) When grown lattice-matched along the a-axis of GaN, AlInN has a higher contrast in refractive indices to GaN compared to AlGaN, 6,7) making it a promising choice for application in distributed Bragg-reflectors 6) and cladding layers. 8,9) However, epitaxial growth of AlInN of high crystalline quality remains a challenging endeavour, struggling with intrinsic degradation of the crystal quality 10,11) and phase separation, [12][13][14][15] especially for thick layers and high indium concentrations. 16) Reference 17 observed a dependence of the indium concentration of AlInN on its layer thickness in c-plane AlInN/GaN superlattice structures and concluded the formation of an approximately 0.4 nm thick layer of pure AlN during the initial stage of growth.…”

Room-temperature continuous-wave operation of GaN-based vertical-cavity surface-emitting lasers with n-type conducting AlInN/GaN distributed Bragg reflectors

“…21) Regarding the conductivity, it must be considered that the large polarization charges induced at the AlInN=GaN inter-faces markedly affect the vertical conductivity through the interfaces. 26) We then proposed and developed a new concept of modulation doping for a nitride-based DBR to neutralize the large polarization charges with ionized donors. 22,27) In this study, we developed n-type conducting AlInN=GaN DBRs and demonstrated the room-temperature continuouswave (CW) operation of a GaN-based VCSEL utilizing the n-type conducting AlInN=GaN DBR.…”