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HL: Fachverband Halbleiterphysik
HL 8: Nitrides: Devices
HL 8.3: Vortrag
Montag, 16. März 2020, 10:00–10:15, POT 51
GaN:Ge as transparent conductive nitride contact layer for blue tunnel-junction LEDs — •Christoph Berger, Silvio Neugebauer, Cleophace Seneza, Hartmut Witte, Jürgen Bläsing, Armin Dadgar, and André Strittmatter — Otto-von-Guericke-Universität Magdeburg
Using germanium as a shallow donor for n-type GaN films grown by metalorganic vapor-phase epitaxy, we achieve very high electron concentrations of up to 2 x 1020 cm-3 and low specific bulk resistivities down to 3 x 10-4 Ωcm. Under optimized growth conditions, no degradation of the crystalline quality is observed and layers exhibit high optical transparency making highly doped GaN:Ge very attractive for different application fields. One promising application of such n++-layers is the achievement of transparent conductive nitride (TCN) contacts with excellent current spreading on top of LEDs, edge emitting laser diodes or vertical-cavity surface-emitting lasers (VCSELs). Such intrinsic TCN contacts offer significant lower absorption than conventionally used Iindium Tin Oxide layers, which is helpful to increase the output power of light emitting devices or to decrease the threshold current for VCSELs. Therefore, we realized tunnel-junction LEDs by capping conventional pn-LED structures with TCN contacts using GaN:Ge layers. We will discuss structural, electrical and optical characteristics of fabricated tunnel junction LEDs and compare them with standard LEDs.