SBIR-STTR Award

The proposed innovation is germanium power semiconductor devices (diodes and transistors) developed specifically for power-management and actuator-control circuits operating at low and cryogenic temperatures. This is important for upcoming space missions to extremely cold environments, because it can greatly reduce the need for thermal control and required spacecraft power. These missions include those to the outer planets and other cold sites of primary interest in the Solar System, such as Europa as well as interstellar missions. Preliminary measurements confirm that Ge diodes and some types of Ge bipolar transistors can operate down to the required deep cryogenic temperatures, namely the vicinity of liquid-helium temperature (4K). The objective of this Phase I effort is to demonstrate the advantages of Ge devices for cryogenic power applications and to determine the feasibility of producing the necessary types of devices. Deliverables will include working prototypes with characterization at 4K and 77K and the identification of promising technologies for fuller implementation in Phase II.

Potential Commercial Applications:
Industrial and commercial applications that could potentially benfit from cryogenic high-power electronics include (1) Medical diagnostics, in particular magnetic resonance imaging (MRI) equipment, (2) High-frequency, high-power amplifiers, especially those coupled to superconducting components, (3) Motors and generators operating at cryogenic temperatures and/or based on superconductors, (4) Power transmission and distribution that uses superconducting cables or transformers, (5) High-power transmission and distribution, (6) Energy storage systems used for "sag" protection and load leveling, based on magnetic energy, (7) Magnetic confinement systems.

The proposed innovation is germanium (Ge) power semiconductor devices (diodes and transistors) developed specifically for power-management and actuator-control circuits operating at cryogenic temperatures. In Phase I we demonstrated that all types of Ge devices, diodes, bipolar junction transistors and field-effect transistors, can operate down to 20 K, and that GPD has the capability to design, fabricate and characterize these devices at these low temperatures. Si-based devices, by contrast, cannot match the performance of germanium devices at 80 K and lower. In Phase II, we will continue development of Ge-based devices designed specifically for cryogenic power electronics with the aim of improved efficiency and reduced size beyond the current state-of-the-art. Through collaboration with potential users, we will establish target performance criteria for Ge diodes and transistors (junction field-effect, MOS, as well as insulated gate bipolar devices). We will design, fabricate, test, and distribute these devices to get feedback, leading to the release of these devices as a commercial product line. POTENTIAL COMMERCIAL APPLICATIONS There are applications for cryogenic power electronics in the Space, Medical, Utilities, Communications, Defense and Scientific areas. NASA and other agencies have upcoming and envisioned projects involving cryogenic temperatures, which require power management and many will require drive electronics for actuators and motors (to aim space telescope mirrors for example). Magnetic Resonance Imaging equipment uses superconducting magnets and could benefit from increased performance using cryogenic power electronics. Cryogenic power transmission and distribution systems will require compatible electronics. The U.S. Navy is developing superconducting motors in its pursuit of the "all electric" ship, which will need sub-77 K electronics. High-frequency, high-power amplifiers such as those used for cell-phone base stations already use some cryogenic components and would benefit from the proposed power electronics technology