German Scientists Successfully Apply New Technology to Grow High-Quality Germanium Single Crystals

Introduction

Recently, Ch. Frank-Rotsch and P. Rudolph from the Leibniz Institute for Crystal Growth in Berlin, Germany, published an article titled "Vertical Gradient Freeze growth of 4-inch germanium single crystals in a heater magnet module" in the Journal of Crystal Growth. This research demonstrates a new method for growing 4-inch germanium single crystals using a traveling magnetic field (TMF) generated by a heater-magnet module (HMM) through the vertical gradient freeze (VGF) technique, achieving significant progress in energy efficiency and crystal quality. This breakthrough has attracted widespread attention in the industry.

Innovative Crystal Growth Technology

Traditional germanium single crystal growth methods suffer from high energy consumption and unstable crystal quality. To overcome these challenges, researchers combined the VGF method with TMF generated by HMM for the first time to grow 4-inch germanium single crystals. This innovative HMM was integrated into the industrial Bridgman equipment "Kronos," replacing the standard meandering heater.

The HMM utilizes a coil-like design, using direct current (DC) for heating and phase-accelerating current (AC) to generate TMF. Three coil segments are connected via a star-shaped wiring, optimizing the amplitude, frequency, and phase shift of the TMF. Through numerical simulations and experimental verification, researchers found that low field frequencies of 20-50 Hz are most suitable. This innovative design greatly improves the energy efficiency of the crystal growth process while ensuring the stability of crystal quality.

High-Quality Germanium Single Crystals

The first batch of germanium single crystals grown under near-optimal conditions exhibited excellent performance. These single crystals have significantly reduced macroscopic and microscopic inhomogeneities, relatively low dislocation densities of (3-10)×10^2 cm^-2, and carrier mobility as high as 2800 cm^2V^-1s^-1. These indicators have reached international advanced levels.

The growth of these high-quality germanium single crystals benefits from carefully designed experimental procedures and advanced equipment. Researchers utilized TMF generated by HMM and pyrolytic boron nitride (pBN) crucibles in the commercial VGF equipment "Kronos." The crystal growth process is driven by computer-controlled gradient propagation, ensuring the stability and repeatability of growth conditions.

Numerical Simulations to Optimize Growth Conditions

To further optimize crystal growth conditions, researchers conducted extensive numerical simulations using the CrysMAS code. These simulations aimed to investigate the generation mechanism of Lorentz force density and find the optimal solid-liquid interface shape. By simulating different TMF parameter combinations, researchers obtained valuable theoretical guidance and provided important references for experiments.

The research method combining numerical simulations and experiments greatly improves research efficiency and shortens the optimization cycle. This method is not only applicable to the growth of germanium single crystals but can also be extended to the crystal growth research of other semiconductor materials.

Significance of High-Quality Germanium Single Crystals

Germanium single crystals are important materials in the electronic and optoelectronic fields, with wide applications in high-performance devices, infrared optics, solar cells, and more. However, traditional germanium single crystal growth methods face numerous challenges, limiting the quality improvement and cost reduction of germanium single crystals.

This research demonstrates the great potential of the KRISTMAG concept. By introducing TMF into the VGF growth process, it can significantly improve the energy efficiency of crystal growth and effectively control the interface morphology, enhancing the structural perfection and carrier mobility of germanium single crystals. This provides new ideas and methods for producing high-quality, low-cost germanium single crystals.

With the rapid development of emerging technologies such as 5G communication, artificial intelligence, and the Internet of Things, the demand for high-quality germanium single crystals is growing. The breakthrough progress of this research is expected to promote the upgrading of the germanium single crystal industry and provide continuous material support for innovation and development in related fields.

The Important Role of pBN Crucibles

In this research, pBN crucibles played a crucial role. pBN crucibles are widely used in the field of crystal growth due to their excellent high-temperature stability, corrosion resistance, and thermal conductivity. Especially in the germanium single crystal growth process, pBN crucibles have good wettability with molten germanium, with a contact angle of up to 170 degrees, which helps minimize the interaction between molten germanium and crucible walls, thereby obtaining high-quality single crystals.

As one of the major pBN crucible manufacturers on the market, QSAM Inc. has been committed to providing high-quality customized services for scientific research users. Through close cooperation with researchers, QSAM Inc. continuously optimizes the design and manufacturing process of pBN crucibles to meet the requirements of different material systems and growth conditions. High-quality pBN crucibles provide reliable hardware support for crystal growth research.

Future Prospects

With the continuous advancement of science and technology, the demand for semiconductor materials is also growing. High-performance electronic and photonic devices require higher crystal quality, which drives scientists like Frank-Rotsch and Rudolph to continuously explore and innovate more efficient and higher-quality crystal growth technologies. In this process, companies like QSAM Inc. play a vital role; they not only provide the necessary high-quality materials but also contribute to scientific research progress.

As this technology develops and matures, we can expect to see more high-performance semiconductor devices in the future. They will enable various fields of modern technology with higher efficiency and lower costs.