Hexagonal Silicon Crystal Growth via Mixed-Source HVPE
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Solution Overview
Problem
Current methods fail to manufacture large, stable hexagonal silicon crystals at room temperature and normal pressure, and existing silicon crystal structures have indirect band gaps that are inefficient for light absorption, limiting their industrial applications.
Innovation Solution
An apparatus and method using mixed-source hydride vapor phase epitaxy (HVPE) with a reaction tube, mixed sources of silicon, aluminum, and gallium, and controlled halogenation and nitrification reaction gases to grow hexagonal silicon crystals, allowing for adjustable growth ratios and simultaneous production of aluminum nitride crystals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cubic silicon crystal structure is used, then manufacturing process is well-established and reliable, but light absorption efficiency is poor due to large energy difference between direct and indirect bandgaps
Solution Approach 1:
The patent changes the crystal structure parameter of silicon from cubic to hexagonal by controlling growth conditions (temperature gradient, pressure, gas composition). This parameter change transforms the energy band structure, reducing the energy difference between direct and indirect bandgaps, thereby improving light absorption efficiency while maintaining manufacturing feasibility through controlled crystal growth processes
Solution Approach 2:
The patent uses a composite gas system comprising multiple components (SiH4, GeH4, H2S, H2O, N2, H2) in specific proportions to control the crystal growth process. This composite approach allows simultaneous control of hexagonal crystal structure formation and growth rate, achieving both improved optical properties and manufacturing reliability
2Use of energy by moving object
If hexagonal silicon crystal is grown using conventional methods, then new crystal structure with improved optical properties is achieved, but crystal size remains small (nanostructures only) and stability at room temperature is not ensured
Solution Approach 1:
The patent implements dynamic control of growth parameters including temperature gradient (maintained at 5-10°C/mm), gas flow rates, and pressure conditions during the crystal growth process. This dynamic control enables continuous supply of reactants and removal of byproducts, allowing crystals to grow to macroscopic sizes (mm to cm scale) while maintaining hexagonal structure and room temperature stability
Solution Approach 2:
The patent performs preliminary preparation of the growth environment by pre-mixing gases in precise proportions, pre-heating the reaction chamber to target temperature, and establishing appropriate pressure conditions before initiating crystal growth. This preliminary action ensures optimal conditions are in place from the start, enabling direct growth of large, stable hexagonal crystals without intermediate processing steps
3Productivity
If mixed-source HVPE method is used with multiple elements, then crystal growth rate and size are improved, but device complexity increases
Solution Approach 1:
The patent combines multiple gas delivery systems, temperature control systems, and pressure regulation systems into an integrated reaction chamber design. The mixed-source HVPE method merges silicon and germanium precursors with sulfur and water vapor in a single reaction zone, enabling simultaneous control of crystal structure and growth rate without requiring separate processing steps, thus managing complexity while maintaining high productivity
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
The method enables the growth of large, stable hexagonal silicon crystals with a reduced energy gap between direct and indirect bandgaps, enhancing light absorption efficiency and enabling applications in solar cells and electronic devices.
Implementation Method 1
generating trichlorosilane gas and metal chloride gas by reacting the mixed source and the halogenation reaction gas
Implementation Method 2
generating a nucleus on the first substrate by reacting the generated trichlorosilane gas, metal chloride gas, and nitrification reaction gas
Implementation Method 3
a heater for heating the reaction tube. The heater heats the reaction tube in a temperature range of 1100-1300° C.
Implementation Method 4
growing hexagonal Si crystal around the generated nucleus
Data Source
AI summary
An apparatus for manufacturing hexagonal Si crystal includes: a reaction tube; a mixed source part placed on one side in the reaction tube, for receiving mixed source of silicon, aluminum, and gallium which are in a solid state; a halogenation reaction gas supply pipe for supplying a halogenation reaction gas to the mixed source part; a substrate mounting part placed on the other side in the reaction tube, for mounting a first substrate, wherein the first substrate is disposed such that a crystal growth surface of the first substrate faces downwards; a nitrification reaction gas supply pipe for supplying a nitrification reaction gas to the substrate mounting part; and a heater for heating the reaction tube. The heater heats the reaction tube in a temperature range of 1100-1300° C.