Vertical High-Pressure Reactor for Nitride Crystal Growth
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional ammonothermal methods for growing group III nitride crystals are limited by the small diameter of high-pressure reactors due to material constraints, leading to reduced crystal growth rates and increased dislocation density, as the reactor length cannot be extended without compromising growth conditions.
Innovation Solution
A high-pressure reactor with a cylindrical design where the nutrient is placed along the longitudinal axis and seed crystals are positioned near the reactor wall, eliminating baffles to ensure uniform temperature and minimizing convective flow, allowing for longer reactor lengths without affecting growth rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the reactor length is extended to grow more crystals per batch, then the productivity increases, but the crystal growth rate decreases and dislocation density increases due to compromised growth conditions
Solution Approach 1:
The patent transitions from a conventional horizontal reactor configuration to a vertical reactor configuration, utilizing the vertical dimension to accommodate longer reactor length. This dimensional change allows extended reactor length (L/D ratio of 10:1 to 20:1) without compromising the radial growth conditions, enabling more crystals to be grown per batch while maintaining crystal quality through optimized nutrient distribution and convective flow patterns in the vertical orientation
2Productivity
If the reactor diameter is increased to accommodate more crystals, then the productivity increases, but the reactor cannot be made larger due to material constraints of high-pressure reactor construction
Solution Approach 1:
The patent exploits the vertical dimension by orienting the reactor vertically with a high length-to-diameter ratio (10:1 to 20:1). This allows the reactor length to be extended significantly without increasing the diameter, thereby bypassing material constraints on reactor size while still accommodating more crystals through the extended vertical space
Solution Approach 2:
The patent segments the reactor into multiple growth zones along its length, with nutrient containers positioned at different vertical locations. This segmentation allows efficient utilization of the extended vertical space, with each segment contributing to crystal growth while maintaining optimal nutrient distribution and convective flow patterns throughout the reactor length
3Manufacturing precision
If baffles are added to separate nutrient and crystal growth regions, then the growth conditions are optimized, but the temperature uniformity decreases and convective flow increases
Solution Approach 1:
The patent removes baffles from the reactor design, extracting the flow-directing function while maintaining growth condition control through alternative means. Nutrient containers are positioned strategically along the vertical axis, and natural convection patterns in the vertical orientation provide sufficient nutrient transport without requiring baffle-induced flow, thereby preserving temperature uniformity
Solution Approach 2:
The patent creates equipotential temperature conditions throughout the reactor by eliminating baffles that would create temperature gradients. The vertical orientation with external heating provides uniform heat distribution, and the natural convective flow patterns ensure uniform nutrient and heat distribution throughout the reactor volume, maintaining isothermal conditions favorable for high-quality crystal growth
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 configuration enables the growth of more crystals per batch with reduced dislocation density and improved crystal quality, as all seed crystals maintain similar growth rates and are closer to the nutrient, enhancing the efficiency of crystal production.
Implementation Method 1
growing group III nitride crystals in supercritical ammonia
Implementation Method 2
the solution of supercritical ammonia, gallium, and additives to contact both faces of the seed crystal
Implementation Method 3
The reactor is heated by external heaters so that the temperature of the reactor becomes practically uniform
Data Source
AI summary
Provided is a high-pressure reactor suitable for a high-pressure process using supercritical ammonia grow bulk crystal of group III nitride having lateral dimension larger than 2 inches or to form various transition metal nitrides. The reactor has nutrient distributed along the reactor's longitudinal axis and seed material positioned at the reactor's inner wall and along the reactor's longitudinal axis. Nutrient diffuses through supercritical ammonia from the reactor's longitudinal axis and deposits on the seed material positioned by the reactor's inner wall. Both the nutrient and seed material are heated by the same heater. Material growth can primarily be due to material diffusion through supercritical ammonia. This configuration and methodology reduce convective movement of supercritical ammonia due to temperature differential, providing a more quiescent environment in which group III nitride or transition metal nitride is formed.