Advancements in multi-junction semiconductors

Nature offers three compound types: conductive, semi-conductive, and insulative. Semiconductors fall in the middle, opening and closing electrical circuits under certain conditions. Most semiconductors are built from crystalline powder materials like silicon (Si), gallium (Ga), selenium (Se), copper (Cu), cadmium (Cd), and germanium (Ge). Each of these compounds brings unique properties to semiconductor applications, such as varied heat tolerances, light refraction indexes, and electron availability.

Semiconductors power everyday electronic devices, serving industries from consumer electronics to aerospace and military defense. Microchips are one example, performing tasks through integrated circuits made from semiconductor materials. External factors like circuit design, purity, and material quality influence microchip efficiency. These factors, along with temperature, magnetic fields, and light, play a critical role in determining performance.

In 1947, researchers used germanium to create the first working transistor. Over time, high-purity silicon replaced germanium due to its availability, lower cost, and better heat resistance. Silicon also has fewer free electrons, giving it a lower conductivity than germanium. Although silicon still dominates semiconductor production, technological advancements are bringing germanium back into focus. Today, germanium shows promise for applications in aerospace, defense, microchips, and photovoltaics.

Around 1980, germanium found new applications in gamma-ray detectors, infrared detectors, and fiber optics for NASA. It remains valuable in high-speed transistors, specialized semiconductors, plastic resins, and as a colorant in glass production. Silicon semiconductors continue to serve everyday electronics well, but as systems grow more complex, silicon faces limits in efficiency and speed. Continued research now highlights germanium as an adaptable material suited for high-demand technology.

Germanium is an inorganic byproduct of zinc ore processing. The United States classifies it as a critical mineral due to its importance in defense and telecommunications. With an annual production of 140 metric tons globally, most germanium processing happens in China, which produces 95 metric tons each year. Past producers in Africa stopped extraction due to environmental and regulatory concerns. Germanium’s high electron availability and conductivity make it ideal for multi-junction cells and applications requiring fast electron transfer.

Germanium-based multi-junction solar cells have gained popularity in high-demand applications. These cells contain multiple p-n junctions that produce current at different wavelengths. Germanium, silicon, and indium all respond to different wavelengths, creating efficient energy generation. Germanium cells offer greater power efficiency, lower weight, and reduced production costs, making them suitable for defense and aerospace use.

Germanium withstands extreme environments like space, where there’s no protective ozone layer. In these conditions, radiation levels are high, and solar cells face damage from proton and electron bombardment, which reduces their lifespan. Germanium’s resilience to harsh temperatures supports long-term durability, reducing costs and enhancing efficiency for satellites in orbit. This durability allows smaller, more compact satellites, saving on launch costs due to weight reduction.

Chips perform basic functions with binary choices—1 or 0, on or off. Advances in germanium research now show potential in artificial intelligence and neural networks, where adaptable chip functions and direct circuit changes are needed. Experimental research into germanium’s properties opens new possibilities, potentially enhancing transistor function and chip circuits. Germanium could support AI technology development and semiconductor efficiency, helping overcome current limitations.

Although germanium-based photovoltaic cells offer higher efficiency, silicon-on-glass (SoG) cells dominate the global solar market. SoG cells are cheaper, despite causing chromatic aberrations. The solar industry seeks more efficient, low-cost solutions to reduce greenhouse gases. Multi-junction cells with concentrated solar optics show potential for enhanced solar power, but high costs still hinder widespread use. With advancements in germanium powder technology and semiconductor design, large-scale consumer applications may become feasible in the solar industry.