GaP p-contact layer and transparent conductive oxide for optoelectronic chips
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Solution Overview
Problem
Optoelectronic semiconductor chips with thick current spreading layers face issues of high optical absorption and increased moisture sensitivity, particularly when emitting short-wave radiation or having low aluminium content in the current spreading layer.
Innovation Solution
The use of a semiconductor layer sequence with a p-type semiconductor region, an n-type semiconductor region, and an active layer, where the current spreading layer is made of a transparent conductive oxide and includes a thin p-contact layer of C-doped GaP with a high dopant concentration, and a metallic p-connection layer, which reduces absorption and moisture sensitivity by minimizing the thickness and aluminium content of the p-contact layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a thick current spreading layer of AlGaAs is used, then good current spreading is achieved, but optical absorption increases significantly
Solution Approach 1:
The current spreading function is divided between two separate layers: a thin p-contact layer (less than 100 nm) that provides electrical contact and a transparent conductive oxide layer that provides current spreading. This segmentation allows each layer to be optimized for its specific function, with the transparent conductive oxide being thin enough to minimize absorption while still providing effective current spreading.
Solution Approach 2:
The invention changes the material parameters by using a transparent conductive oxide with specific optical properties (high transparency in the emission wavelength range) and controlling the thickness and doping concentration of the p-contact layer. The C-doping concentration is specifically controlled at at least 5×10^19 cm^-3 to achieve the desired electrical conductivity while maintaining low absorption.
2Loss of energy
If the aluminium content in the current spreading layer is increased, then optical absorption is reduced, but moisture sensitivity increases
Solution Approach 1:
The transparent conductive oxide acts as an intermediary layer between the p-contact layer and the external environment. This layer provides the necessary current spreading function while being inherently more resistant to moisture than high-aluminium-content AlGaAs layers, thus mediating between the electrical and optical requirements without introducing moisture sensitivity.
3Reliability
If a thin p-contact layer with low aluminium content is used, then moisture sensitivity is reduced, but current spreading capability decreases
Solution Approach 1:
The current spreading function is divided between two separate layers: a thin p-contact layer (less than 100 nm) that provides electrical contact and a transparent conductive oxide layer that provides current spreading. This segmentation allows each layer to be optimized for its specific function, with the transparent conductive oxide being thin enough to minimize absorption while still providing effective current spreading.
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
This configuration results in an optoelectronic semiconductor chip with low optical absorption and improved moisture resistance, maintaining high electrical conductivity and reducing radiation absorption losses.
Implementation Method 1
the p-contact layer contains GaP doped with C, a C dopant concentration in the p-contact layer is at least 5*10^19 cm^-3
Implementation Method 2
a current spreading layer including a transparent conductive oxide adjoining the p-type semiconductor region
Implementation Method 3
the p-contact layer is less than 100 nm thick... reduces absorption and moisture sensitivity by minimizing the thickness
Data Source
AI summary
An optoelectronic semiconductor chip including a semiconductor layer sequence containing a phosphide compound semiconductor material, wherein the semiconductor layer sequence includes a p-type semiconductor region, an n-type semiconductor region and an active layer disposed between the p-type semiconductor region and the n-type semiconductor region, a current spreading layer including a transparent conductive oxide adjoining the p-type semiconductor region, and a metallic p-connection layer at least regionally adjoining the current spreading layer, wherein the p-type semiconductor region includes a p-contact layer adjoining the current spreading layer, the p-contact layer contains GaP doped with C, a C dopant concentration in the p-contact layer is at least 5*1019 cm−3, and the p-contact layer is less than 100 nm thick.