Vertical Laser Diode Release for Precise Cavity and Mirror Alignment
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Solution Overview
Problem
Conventional methods for producing vertically emitting semiconductor laser diodes with nitride compound semiconductor materials face challenges in precisely adjusting the thickness of the epitaxial semiconductor layer sequence and aligning mirrors, leading to inaccuracies in optical resonator alignment and wavelength control.
Innovation Solution
A method involving electrochemical etching to detach the growth substrate, using a sacrificial layer and a carrier with cavities or cut-outs to precisely control the thickness and alignment of the epitaxial semiconductor layer sequence, allowing for precise adjustment of the optical cavity length and alignment of mirrors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional detachment methods are used, then the growth substrate can be removed, but the thickness of the epitaxial semiconductor layer sequence cannot be precisely controlled
Solution Approach 1:
A sacrificial layer is deposited on the growth substrate before epitaxial growth of the semiconductor layer sequence. This preliminary action enables precise thickness control during subsequent detachment, as the sacrificial layer acts as a template that defines the final thickness of the released semiconductor layers.
Solution Approach 2:
The sacrificial layer serves as an intermediary between the growth substrate and the epitaxial semiconductor layer sequence. It facilitates controlled detachment while maintaining precise thickness control, as the sacrificial layer can be selectively removed to release the semiconductor layers at the desired thickness.
2Manufacturing precision
If mirrors are aligned after growth, then the laser diode can be assembled, but alignment accuracy of the optical resonator is compromised
Solution Approach 1:
Mirror layers are deposited on the growth substrate before the semiconductor layer sequence is detached. This preliminary alignment ensures that when the semiconductor layers are released and transferred to the carrier, the mirrors are already positioned with high precision relative to the optical path, eliminating the need for complex post-assembly alignment procedures.
Solution Approach 2:
The mirror deposition and semiconductor layer growth are combined in a single integrated process on the growth substrate. This merging of operations ensures that the mirrors and semiconductor layers are co-aligned with high precision, as both are formed in the same coordinate system before detachment.
3Manufacturing precision
If the epitaxial layer sequence is made thicker, then the optical cavity length increases, but wavelength control accuracy decreases
Solution Approach 1:
The thickness of the epitaxial semiconductor layer sequence is precisely controlled by adjusting growth parameters during metal-organic vapor phase epitaxy. By changing parameters such as temperature, pressure, and precursor flow rates, the layer thickness can be accurately controlled to achieve the desired optical cavity length and corresponding wavelength precision.
Solution Approach 2:
Mechanical thickness control methods are replaced with precise electrochemical detachment control. The sacrificial layer thickness, which determines the final semiconductor layer thickness after detachment, is controlled through electrochemical etching parameters, enabling sub-micron precision in optical cavity length and wavelength control.
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
Enables precise control of the epitaxial semiconductor layer sequence thickness and alignment of mirrors, improving the accuracy of wavelength control and optical resonator alignment, enhancing the performance of vertically emitting semiconductor laser diodes.
Implementation Method 1
the sacrificial layer is dissolved by electrochemical etching, whereby the growth substrate is detached and the remaining epitaxial semiconductor layer sequence has a thickness that is as precisely defined as possible
Implementation Method 2
an active layer for generating electromagnetic radiation
Data Source
AI summary
The invention relates to a method for producing a multiplicity of vertically emitting semiconductor laser diodes, including providing a growth substrate, epitaxially growing an epitaxial semiconductor layer sequence including an active layer for generating electromagnetic radiation and including a sacrificial layer, wherein the sacrificial layer is disposed between the growth substrate and the active layer, forming trenches in the semiconductor layer sequence, resulting in a multiplicity of semiconductor layer stacks being formed and portions of the sacrificial layer being exposed, applying a carrier onto the epitaxial semiconductor layer sequence, and detaching the growth substrate by electrochemically etching the sacrificial layer, wherein an electrochemical etchant has access to the sacrificial layer through a cut-out in the growth substrate and/or through a cavity in the carrier. The invention also relates to a vertically emitting semiconductor laser diode.