GaN Tunneling Structures Eliminate P-Doping for Efficient Light Emission
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Solution Overview
Problem
Gallium nitride (GaN) based light emitters face challenges due to the high resistivity of p-doped regions, which leads to non-uniform carrier spreading, increased resistivity, and reduced efficiency in light emission, particularly in high current density applications, as well as difficulties in p-type doping and processing.
Innovation Solution
The development of unipolar-doped GaN resonant tunneling structures that eliminate the need for p-type doping by using interband tunneling to generate holes through Zener tunneling, allowing for efficient hole generation and radiative recombination with electrons, thereby enabling efficient light emission without a p-n junction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If p-type doping is used in GaN based light emitters, then hole injection is achieved, but high resistivity and non-uniform carrier spreading occur
Solution Approach 1:
The patent removes the p-doped GaN layer entirely from the device structure. Instead of using p-type doping to provide holes, the invention uses n-type GaN quantum wells that generate holes through Zener tunneling and impact ionization mechanisms, thereby eliminating the high resistivity and non-uniform carrier spreading problems associated with p-type doping.
Solution Approach 2:
The patent changes the fundamental parameter of doping type from bipolar (p-type and n-type) to unipolar (n-type only). By using n-type GaN quantum wells with specific doping concentrations and well widths, the device achieves hole generation through quantum mechanical tunneling and impact ionization, transforming the carrier injection mechanism while maintaining light emission functionality.
2Reliability
If p-type doping is used, then holes are provided for recombination, but processing difficulty and additional materials are required
Solution Approach 1:
The patent extracts and eliminates the p-doped GaN layer from the device structure. The hole provision function is transferred to the n-type GaN quantum well region, where holes are generated in-situ through Zener tunneling and impact ionization processes, removing the need for separate p-type doping materials and high-temperature rapid thermal annealing processes.
Solution Approach 2:
The n-type GaN quantum well structure provides its own hole generation capability through internal quantum mechanical processes (Zener tunneling and impact ionization). This self-service mechanism eliminates the need for external p-type doping layers and complex processing steps, simplifying both material requirements and fabrication procedures.
3Illumination intensity
If high current density is applied, then light emission intensity increases, but resistive heating and voltage drop increase
Solution Approach 1:
The patent removes the high-resistivity p-doped GaN layer that causes significant voltage drop and Joule heating. By replacing it with an n-type quantum well structure that generates holes through tunneling and impact ionization, the device achieves lower series resistance and reduced resistive heating, enabling higher current densities to be applied without excessive thermal losses.
Solution Approach 2:
The patent changes the electrical resistance parameter by using n-type doping throughout the structure instead of p-type doping at the contact region. The n-type GaN quantum wells have lower resistivity and better carrier mobility, reducing the voltage drop and resistive heating when high current densities are applied, thereby improving overall device efficiency.
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 improved light emission efficiency, reduced thermal issues, and simplified fabrication, as well as the ability to generate high-density holes and electron currents through distinct physical mechanisms, enhancing the performance of GaN-based LEDs and lasers.
Implementation Method 1
The development of unipolar-doped GaN resonant tunneling structures that eliminate the need for p-type doping by using interband tunneling to generate holes through Zener tunneling
Implementation Method 2
GaN resonant tunneling structures that eliminate the need for p-type doping by using interband tunneling to generate holes
Implementation Method 3
allowing for efficient hole generation and radiative recombination with electrons, thereby enabling efficient light emission
Data Source
AI summary
Gallium nitride based devices and, more particularly to the generation of holes in gallium nitride based devices lacking p-type doping, and their use in light emitting diodes and lasers, both edge emitting and vertical emitting. By tailoring the intrinsic design, a wide range of wavelengths can be emitted from near-infrared to mid ultraviolet, depending upon the design of the adjacent cross-gap recombination zone. The innovation also provides for novel circuits and unique applications, particularly for water sterilization.