P-type Nitride Semiconductor Layer Formation via Gas Flow Control
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Solution Overview
Problem
Conventional methods for manufacturing p-type nitride semiconductors often result in high resistivity and thermal damage to nitride semiconductor layers, particularly those containing In, due to the need for annealing treatments, which hinder the production of low-resistivity p-type nitride semiconductors with high reproducibility.
Innovation Solution
A method involving metal organic chemical vapor deposition using a nitrogen carrier gas and hydrogen carrier gas with specific flow ratios, along with controlled ammonia and dimethyl hydrazine concentrations, to form a nitride semiconductor layer without the need for extensive annealing, ensuring low resistivity and high reproducibility of p-type conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If annealing treatment is performed after crystal growth to eliminate hydrogen, then p-type conductivity is achieved, but thermal damage occurs to nitride semiconductor layers containing In
Solution Approach 1:
The patent applies preliminary action by controlling the carrier gas composition (hydrogen to nitrogen ratio ≥ 0.75%) and adding ammonia during the crystal growth process itself, rather than performing annealing after growth. This preliminary control of hydrogen content and nitrogen supply during growth activates p-type impurities in-situ, eliminating the need for subsequent thermal annealing that would cause damage to In-containing layers
2Quantity of substance
If conventional MOCVD method with p-type doping is used, then nitride semiconductor layer is formed, but resistivity remains significantly high
Solution Approach 1:
The patent applies parameter changes by optimizing the hydrogen to nitrogen carrier gas flow ratio to at least 0.75% and controlling ammonia concentration at 0.1-30 vol% during crystal growth. These parameter changes enable electrical activation of p-type impurities during growth, achieving low resistivity (≤ 10^-3 Ωcm) and high carrier concentration (≥ 2.4×10^18 cm^-3) without requiring post-growth annealing
3Manufacturing precision
If annealing treatment is performed to reduce resistivity, then p-type conductivity improves, but manufacturing time and process complexity increase
Solution Approach 1:
The patent performs the resistivity-reducing action preliminarily during crystal growth by controlling carrier gas composition and ammonia concentration, rather than requiring a separate post-growth annealing step. This integrates the activation process into growth itself, reducing total manufacturing time and simplifying the process while achieving resistivity ≤ 10^-3 Ωcm
Solution Approach 2:
The patent merges the crystal growth process with the p-type activation process by controlling gas composition and ammonia addition during growth. This combines two previously separate steps (growth + annealing) into one integrated process, improving productivity while maintaining low resistivity
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 enables the production of p-type nitride semiconductor layers with low resistivity and improved luminous efficiency, reducing thermal damage and increasing the yield of nondefective products, while allowing for shorter annealing times if necessary, thus enhancing the performance and reliability of nitride semiconductor-based devices.
Implementation Method 1
a second step of cooling down from the crystal growth temperature by using a second carrier gas containing nitrogen and ammonia
Implementation Method 2
a second step of cooling down from the crystal growth temperature by using a second carrier gas containing nitrogen and ammonia
Data Source
AI summary
The present invention includes a first step of forming a nitride semiconductor layer by metal organic chemical vapor deposition by using a first carrier gas containing a nitrogen carrier gas and a hydrogen carrier gas of a flow quantity larger than that of the nitrogen carrier gas to thereby supply a raw material containing Mg and a Group V raw material containing N, and a second step of lowering a temperature by using a second carrier gas to which a material containing N is added, and hence solves the problems.