VCSEL Tunnel Junction Doping Layout for Stable Oxidation
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Solution Overview
Problem
The high doping concentration of Te or Se in n-type GaAs layers for VCSELs leads to unstable and difficult-to-control oxidation processes, affecting the reliability and performance of VCSELs.
Innovation Solution
Incorporating a first or second tunnel junction with high doping concentration and low resistance into the VCSEL structure, where the n-type semiconductor layers are doped with tellurium and/or selenium and optionally silicon or carbon, allowing for smooth oxidation of the VCSEL oxidation layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the doping concentration of Te or Se in the n-type GaAs layer is increased to achieve high doping concentration and low resistance, then the tunnel junction resistance decreases, but the oxidation process becomes unstable and difficult to control
Solution Approach 1:
The patent divides the n-type semiconductor layer into two distinct layers: a first n-type semiconductor layer with high doping concentration (Te or Se) for low resistance, and a second n-type semiconductor layer with lower doping concentration for stable oxidation. This segmentation allows each layer to fulfill its specific function without compromising the other, resolving the contradiction between low resistance and oxidation stability.
Solution Approach 2:
Different regions of the n-type semiconductor structure are assigned different doping concentrations tailored to their specific functions. The first n-type layer near the tunnel junction has high doping for electrical performance, while the second n-type layer has optimized doping for oxidation process stability. This local quality differentiation enables simultaneous achievement of low resistance and manufacturability.
2Reliability
If the doping concentration of Te or Se is increased to improve carrier tunneling probability, then the tunnel junction resistance decreases, but the oxidation rate becomes slower and less controllable
Solution Approach 1:
The n-type semiconductor region is segmented into two layers with different doping concentrations. The first layer provides high carrier tunneling probability through high Te/Se doping, while the second layer maintains appropriate oxidation rate. This segmentation resolves the contradiction between tunneling efficiency and oxidation productivity.
Solution Approach 2:
The patent changes the doping concentration parameter along the vertical direction of the n-type semiconductor layers. By creating a gradient or stepped structure where doping concentration varies from high to low, the patent optimizes both carrier tunneling (requiring high doping) and oxidation rate (requiring moderate doping), thereby resolving the contradiction between these two parameters.
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 proposed solution enables stable and controlled oxidation processes, improving the reliability and performance of VCSELs by maintaining a high doping concentration while ensuring smooth oxidation.
Implementation Method 1
given the situation that the doping concentrations of the p-type semiconductor layer and the n-type semiconductor layer are sufficiently high, the carrier tunneling probability of the tunnel junction will be higher, and the resistance of the tunnel junction will be lower
Implementation Method 2
When the VCSEL undergoes an oxidation process, an oxidation layer of the VCSEL can be smoothly oxidized
Data Source
AI summary
Provided is a vertical cavity surface emitting laser diode (VCSEL). A tunnel junction with a high doping concentration is provided in the VCSEL. An n-type semiconductor layer of the tunnel junction has stress relative to the substrate, and is doped with at least one element such that the tunnel junction not only has a high doping concentration, but also the epitaxial layer can be oxidized and the oxidation rate is relatively stable during the oxidation process. Alternatively, the n-type semiconductor layer is doped with at least two elements. As a result, the oxidation process of the VCSEL can be stably performed, and the resistance of the tunnel junction with a high doping concentration is low. The tunnel junction is suitable to be arranged between two active layers of the VCSEL or between the p-type semiconductor and the n-type semiconductor layer of the VCSEL.