Effect of low and staggered gap quantum wells inserted in GaAs tunnel junctions

Abstract

In this article, we investigate the impacts of the insertion of either a type I InGaAs or a type II InGaAs/GaAsSb quantum well on the performances of MBE-grown GaAs Tunnel Junctions (TJs). The devices are designed and simulated using a quantum transport model based on the non-equilibrium Green's function formalism and a 6-band k.p hamiltonian. We experimentally observe significant improvements of the peak tunneling current density on both heterostructures with a 460-fold increase for a moderately doped GaAs TJ when the InGaAs QW is inserted at the junction interface, and a 3-fold improvement on a highly doped GaAs TJ integrating a type II InGaAs/GaAsSb QW. Thus the simple insertion of staggered band lineup heterostructures enables to reach tunneling current well above the kA/cm 2 range, equivalent to the best achieved results for Si-doped GaAs TJs, implying very interesting potentials for TJ-based components such as multi-junction solar cells, vertical cavity surface emitting lasers and tunnel-field effect transistors.

Thickness Limitation of Band-to-Band Tunneling Process in GaAsSb/InGaAs Type-II Tunnel Junctions Designed for Multi-Junction Solar Cells

“…Details of the structure can be found in Ref. (24). The structure is almost similar to the TJ-12%-thin structure, but the n+-In 0.12 Ga 0.88 As and p+-GaAs 0.88 Sb 0.12 layer thicknesses are only 6 nm and 4 nm respectively, and the heterojunction is surrounded by degenerately doped GaAs layers instead of low doped GaAs.…”

“…In previously published work, we have proposed an alternative type-II TJ design that consists of incorporating the degenerately doped n+-In 0.12 Ga 0.88 As/p+-GaAs 0.88 Sb 0.12 heterojunction as quantum wells (QWs) into the depletion area of a usual GaAs TJ. Details of the structure can be found in ref .…”

“…In previously published work, we have proposed an alternative type-II TJ design that consists of incorporating the degenerately doped n+-In 0.12 Ga 0.88 As/p+-GaAs 0.88 Sb 0.12 heterojunction as quantum wells (QWs) into the depletion area of a usual GaAs TJ. Details of the structure can be found in ref . The structure is almost similar to the TJ-12%-thin structure, but the n+-In 0.12 Ga 0.88 As and p+-GaAs 0.88 Sb 0.12 layer thicknesses are only 6 and 4 nm, respectively, and the heterojunction is surrounded by degenerately doped GaAs layers instead of low-doped GaAs.…”

Tunnel Junctions for III-V Multijunction Solar Cells Review

“…It is worth noting that improved performance has been achieved in InP based systems with a double quantum well structure [60] and successfully modeled with nonequilibrium Green's function formalism (NEGF) [61]. This modeling approach has also been applied to other tunnel junctions [51,62].…”