Semiconductor Doping via Band Discontinuity Alignment
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Solution Overview
Problem
Controlling doping in wide band gap semiconductor materials, such as Aluminum Gallium Nitride, is challenging due to deep impurity levels and inefficient activation, which limits the conductivity of devices like deep ultraviolet light emitting diodes and nitride-based transistors.
Innovation Solution
A structure with a quantum well and adjacent barrier is designed where the target band discontinuity coincides with the dopant's activation energy, and the doping level is selected to facilitate real space transfer of holes, aligning the dopant energy level with the valence energy band edge or ground state energy of the quantum well, thereby optimizing the actual band discontinuity and doping levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional doping methods are used in wide band gap semiconductor materials, then the doping process is simple, but the impurity activation efficiency is low and conductivity is limited
Solution Approach 1:
The patent changes the energy parameter of the dopant by creating a resonant condition where the dopant energy level aligns with the quantum well energy level. This parameter change transforms the deep impurity level into an effectively shallow level, enabling efficient activation and high conductivity without complicating the doping process
Solution Approach 2:
The quantum well acts as an intermediary energy state that facilitates dopant activation. By introducing this intermediate energy level, holes can be efficiently transferred from the barrier to the quantum well, enabling high conductivity in the wide band gap material
2Reliability
If the dopant energy level is deep in the band gap, then the material maintains its wide band gap properties, but impurity activation is inefficient
Solution Approach 1:
The patent changes the effective activation energy parameter by creating a resonant alignment between the dopant energy level and the quantum well energy level. This transforms the activation energy from a large value (deep impurity level) to a small value (resonant energy difference), enabling efficient thermal activation
3Reliability
If polarization doping is used to create hole accumulation, then lateral conductivity is improved, but perpendicular conductance remains extremely small
Solution Approach 1:
The patent transitions from two-dimensional hole gas (lateral conduction only) to three-dimensional hole accumulation by introducing vertical hole transport through resonant tunneling. The quantum well serves as an energy bridge that enables holes to move perpendicular to the heterostructure interface
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 reduces the activation energy for dopants, enhancing the efficiency of hole transfer and improving the conductivity of semiconductor devices, particularly in deep ultraviolet light emitting diodes and nitride-based transistors.
Implementation Method 1
a target doping level for the quantum well and/or adjacent barrier can be selected to facilitate a real space transfer of holes across the barrier
Implementation Method 2
A target band discontinuity between the quantum well and the adjacent barrier is selected to coincide with an activation energy of a dopant for the quantum well and/or barrier
Implementation Method 3
Polarization doping in GaN-on-AlGaN heterostructures has been shown to lead to the creation of a hole accumulation layer
Implementation Method 4
The transition from a three-dimensional to a two-dimensional hole gas is achieved for hole sheet densities on the order of 10^13 cm^-2 or higher
Data Source
AI summary
A solution for designing and/or fabricating a structure including a quantum well and an adjacent barrier is provided. A target band discontinuity between the quantum well and the adjacent barrier is selected to coincide with an activation energy of a dopant for the quantum well and/or barrier. For example, a target valence band discontinuity can be selected such that a dopant energy level of a dopant in the adjacent barrier coincides with a valence energy band edge for the quantum well and/or a ground state energy for free carriers in a valence energy band for the quantum well. Additionally, a target doping level for the quantum well and/or adjacent barrier can be selected to facilitate a real space transfer of holes across the barrier. The quantum well and the adjacent barrier can be formed such that the actual band discontinuity and/or actual doping level(s) correspond to the relevant target(s).