Laser Doping of Wide Bandgap Semiconductors for Defect Reduction
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Solution Overview
Problem
Current doping methods for wide bandgap semiconductors, particularly silicon carbide, face challenges such as limited dopant species, concentrations, and the creation of defects due to ion implantation, which hinder the development of efficient light emitting diodes and photovoltaic devices.
Innovation Solution
The use of laser doping with unconventional dopants like chromium and europium, which have a valence greater than the parent semiconductor, to create multi-hole acceptors and donors, allowing for efficient radiative states and reducing lattice defects, thereby enhancing the efficiency of solid state energy conversion devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ion implantation is used for doping wide bandgap semiconductors, then dopant can be introduced into the semiconductor, but crystal damage and point defects are created
Solution Approach 1:
The patent replaces the mechanical ion implantation process with a chemical vapor deposition process. Instead of physically bombarding the semiconductor with ions, dopant atoms are delivered through vapor-phase precursors that chemically deposit onto the semiconductor surface, eliminating mechanical damage while achieving desired doping concentrations
Solution Approach 2:
The patent changes the doping mechanism from physical ion implantation to chemical vapor deposition by altering process parameters: using vapor-phase dopant sources, controlling temperature and pressure conditions, and employing chemical reactions to deliver dopant atoms without mechanical impact, thereby maintaining crystal integrity
2Reliability
If high temperature annealing is used to remove implantation defects, then crystal defects can be reduced, but dopant diffusion in previously prepared under layers occurs
Solution Approach 1:
The patent performs doping after all other device fabrication steps are completed. By introducing dopants as the final processing step through chemical vapor deposition, there are no subsequent high-temperature processing steps that would cause unwanted dopant diffusion, thus maintaining precise dopant depth control while still achieving defect-free crystal quality
Solution Approach 2:
The patent uses periodic pulsed doping cycles during chemical vapor deposition, where dopant-containing vapor is introduced in controlled pulses followed by non-dopant vapor periods, allowing precise control of dopant incorporation timing and depth without requiring high-temperature annealing
3Adaptability or versatility
If conventional doping methods are used, then doping can be achieved, but dopant species and concentrations are limited
Solution Approach 1:
The patent employs chemical vapor deposition as a universal doping platform that can accommodate multiple dopant species (boron, phosphorous, arsenic, and other group III-V elements) through different vapor-phase precursors, enabling both n-type and p-type doping with wide concentration ranges without requiring separate implantation processes for each dopant type
Solution Approach 2:
The patent achieves wide dopant concentration ranges by adjusting vapor-phase process parameters including temperature, pressure, precursor flow rates, and exposure time, allowing continuous control from low to high doping concentrations for any given dopant species without being constrained by implantation energy limits
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
Laser doping increases dopant concentrations by several orders of magnitude, reduces lattice defects, and enables the creation of efficient radiative states, improving the performance of light emitting and photovoltaic devices by enhancing electron-hole recombination and operational stability at elevated temperatures.
Implementation Method 1
A thermal energy beam is directed onto the first doped region of the wide bandgap semiconductor material in the presence of the doping gas for converting a portion of the first doped region into a second doped region
Implementation Method 2
A doping gas is applied to the first doped region of the wide bandgap semiconductor material. A thermal energy beam is directed onto the first doped region of the wide bandgap semiconductor material in the presence of the doping gas for converting a portion of the first doped region into a second doped region
Data Source
AI summary
A solid state energy conversion device and method of making is disclosed for converting energy between electromagnetic and electrical energy. The solid state energy conversion device comprises a wide bandgap semiconductor material having a first doped region. A thermal energy beam is directed onto the first doped region of the wide bandgap semiconductor material in the presence of a doping gas for converting a portion of the first doped region into a second doped region in the wide bandgap semiconductor material. In one embodiment, the solid state energy conversion device operates as a light emitting device. In another embodiment, the solid state energy conversion device operates as a photovoltaic device.