Energy band structures for light emitting devices

EP4714235A2Pending Publication Date: 2026-03-25MICROGLASS LLC +1
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Patent Information

Authority / Receiving Office
EP · EP
Patent Type
Applications
Current Assignee / Owner
Filing Date
2024-06-08
Publication Date
2026-03-25

AI Technical Summary

Technical Problem

Compound semiconductor light emitting devices face efficiency drops due to the quantum confined Stark effect and electron leakage, primarily caused by polarization-induced band tilting and non-uniform carrier distribution, which reduces radiative recombination rates and increases non-radiative processes at high current densities.

Method used

The implementation of continuously graded band structures in multi-quantum well structures with minimized or eliminated step discontinuities at quantum well and barrier interfaces, along with smooth electron barrier layers, to reduce polarization effects and enhance carrier confinement and distribution uniformity.

Benefits of technology

This approach mitigates band tilting effects, improves carrier overlap and confinement, and reduces electron leakage, leading to increased quantum efficiency and reduced efficiency droop in light emitting devices, especially for green to ultraviolet wavelengths.

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Abstract

An apparatus and method for reducing the quantum confined Stark effect and electron leakage in polarized compound semiconductors optical gain regions is disclosed. The apparatus comprises a continuously graded multi-quantum well (MQW) band structure wherein the quantum wells (QWs) are concatenated with no quantum barriers (QBs) in between and no more than one heterojunction interface per well. An alternative, equivalent MQW band structure comprises continuously graded QWs separated by continuously graded QBs with no more than one heterojunction interface per well. In both embodiments the band structures are devoid of constant bandgap layers. Non-uniform period and non-uniform bandgap range MQW structures are contemplated. Non-uniform QW / QB thickness ratio MQW structures are also considered. Smoothly graded electron barrier layers (EBLs) with tangent energy bands on the MQW side and no more than one heterojunction interface on the p-injection side may be used to improve electron confinement and hole injection.
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