Dresden 2020 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 8: Nitrides: Devices

HL 8.3: Talk

Monday, March 16, 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.