InGaP Intermediate Layer Si Doping for Light Emitting Devices
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Solution Overview
Problem
The existing light emitting devices with InGaP intermediate layers doped with Si face challenges in achieving stable series resistance reduction and high-speed switching response due to uneven Si concentration and oxidation issues, particularly when using n-type substrates and bonding surfaces.
Innovation Solution
A light emitting device with a double heterostructure of AlGaInP layers and an n-type transparent substrate bonded to an InGaP intermediate layer doped with high concentration Si, where the Si doping is localized and adjusted to maintain bonding strength and reduce series resistance, using MOVPE for epitaxial growth and precise gas flow control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Si is doped at high concentration in the InGaP intermediate layer to decrease series resistance, then series resistance decreases, but Si concentration becomes uneven and oxidation occurs making resistance unstable
Solution Approach 1:
The patent applies local quality by creating a multi-layer structure where the InGaP intermediate layer has different Si doping concentrations in different regions. Specifically, the layer adjacent to the bonding interface has higher Si concentration to reduce contact resistance, while other regions have lower concentration to maintain material quality and prevent oxidation. This spatial variation in doping concentration resolves the contradiction between achieving low resistance and maintaining uniformity.
Solution Approach 2:
The InGaP intermediate layer is segmented into multiple sub-layers with different Si doping concentrations. This segmentation allows each sub-layer to perform its specific function: one sub-layer optimizes for electrical contact while another maintains material stability. The segmented structure prevents the harmful effects of uniform high doping while achieving the desired low series resistance at the bonding interface.
2Device complexity
If n-type substrate and bonding surfaces are used, then device structure is simplified, but series resistance cannot be sufficiently decreased due to Si oxidation
Solution Approach 1:
The patent maintains the simplified n-type device structure while applying local quality by concentrating high Si doping only in the specific sub-layer where it is most effective (adjacent to the bonding interface). This localized approach prevents Si oxidation in other regions while achieving sufficient resistance reduction at the critical contact point, thus maintaining both structural simplicity and electrical performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively decreases series resistance and stabilizes it over time, enhancing the switching response of the light emitting device, especially under high-speed switching conditions, by ensuring even Si distribution and preventing oxidation.
Implementation Method 1
an InGaP intermediate layer, comprising a high concentration Si doping layer having concentrated Si as an n-type dopant formed on the bonding surface side
Implementation Method 2
using MOVPE for epitaxial growth
Implementation Method 3
using MOVPE for epitaxial growth
Data Source
AI summary
A light emitting device comprises a light emitting layer section having a double heterostructure of an n-type cladding layer, an active layer and a p-type cladding layer, each composed of AlGaInP stacked in this order. Supposing a bonding object layer having a first main surface side as p type and a second main surface side as n type, a light extraction side electrode is formed to cover the first main surface partially. An n-type transparent device substrate composed of Group III-V compound semiconductor having greater band gap energy than the active layer is bonded to the second main surface of the bonding object layer. On one sides of the transparent device substrate and the bonding object layer, a bonding surface to the other is formed, and an InGaP intermediate layer is formed to have a high concentration Si doping layer formed on the bonding surface side.