Doped Gallium Arsenide Wafer Solidification for Low Optical Absorption
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Solution Overview
Problem
The production of gallium arsenide single crystals for high-power light-emitting devices faces challenges in achieving low dislocation densities and optical absorption coefficients while maintaining sufficient electric conductivity, particularly in the near infrared range, due to the presence of EL2-defects and dislocations which can lead to device degradation.
Innovation Solution
A process involving the solidification of a gallium arsenide melt with an excess of gallium and a minimum boron concentration of at least 5×10^17 cm^-3, combined with appropriate doping to achieve a charge carrier concentration of 1×10^16 to 1×10^18 cm^-3 and an optical absorption coefficient of ≤2.5 cm^-1 at specific wavelengths, effectively reducing dislocation density and EL2-defect concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the charge carrier concentration is increased to achieve high electric conductivity, then the electric conductivity is improved, but the optical absorption coefficient increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the arsenic molar ratio in the melt (maintaining 0.5 ≤ xAs/(xAs+xGa) < 0.65) and regulating charge carrier concentration within specific ranges (1×10^16 to 1×10^18 cm^-3). This optimization balances electrical conductivity requirements with minimal optical absorption in the near-infrared range, resolving the contradiction between these two parameters.
Solution Approach 2:
The patent implements local quality by creating specific doping conditions in different regions of the crystal growth process. By controlling the arsenic molar ratio and charge carrier concentration locally during solidification, the patent achieves regions with optimized electrical properties while maintaining low optical absorption characteristics in the final crystal structure.
2Reliability
If the dislocation density is reduced to improve device reliability, then the reliability is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent reduces dislocation density by optimizing critical parameters including the arsenic molar ratio (0.5 ≤ xAs/(xAs+xGa) < 0.65) and charge carrier concentration (1×10^16 to 1×10^18 cm^-3). These parameter adjustments create favorable growth conditions that naturally suppress dislocation formation during the VGF or VB crystal growth process, achieving low dislocation density without excessive manufacturing complexity.
3Object-affected harmful factors
If the EL2-defect concentration is reduced to lower optical absorption, then the optical absorption coefficient is reduced, but the charge carrier concentration must be precisely controlled
Solution Approach 1:
The patent reduces EL2-defect concentration by precisely controlling the arsenic molar ratio in the melt (maintaining 0.5 ≤ xAs/(xAs+xGa) < 0.65) and the charge carrier concentration (1×10^16 to 1×10^18 cm^-3). This dual parameter control creates thermodynamic conditions that suppress EL2-defect formation while maintaining adequate electrical conductivity, achieving low optical absorption without excessive doping complexity.
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 approach results in gallium arsenide crystals with low dislocation density, high conductivity, and exceptionally low optical absorption in the infrared range, enhancing the efficiency and longevity of electro-optical devices by reducing the risk of degradation from high electric and optical power densities.
Implementation Method 1
a process for producing gallium arsenide single crystals by solidification of a melt of the semiconductor material
Implementation Method 2
By the additional doping with silicon... By the additional doping of the crystals with elements, which are incorporated into the crystal lattice of gallium arsenide
Data Source
AI summary
A process is disclosed for producing a doped gallium arsenide single crystal by melting a gallium arsenide starting material and subsequently solidifying the gallium arsenide melt, wherein the gallium arsenide melt contains an excess of gallium relative to the stoichiometric composition, and wherein it is provided for a boron concentration of at least 5×1017 cm−3 in the melt or in the obtained crystal. The thus obtained crystal is characterized by a unique combination of low dislocation density, high conductivity and yet excellent, very low optic absorption, particularly in the range of the near infrared.