Cluster D – Devices

This cluster was introduced to highlight the potential of the oxides studied in GraFOx for device-applications. Devices will be processed on layers grown in cluster G and their performance will be investigated.

This cluster addresses the following applications:

1. Lateral and vertical high-voltage power devices (Schottky barrier diodes and field effect transistors). The application of Ga₂O₃ will be evaluated by focusing on the interactions of processing (deposition, etching, and ion implantation) with the (anisotropic) β-Ga₂O₃ material and its influence on device properties and reliability. Open questions to be addressed are electronic trap states in the bulk and at the semiconductor/dielectric interface, a gate oxide that does not break down, suitable etching techniques (dry and wet chemical), Schottky and ohmic contact formation mechanisms, as well as issues related to the reduced thermal conductivity of the Ga₂O₃ material. In addition, the use of deep acceptors or p-type oxides for device insulation will be evaluated.
2. Solar-blind, deep-UV photo detectors based on different polymorphs of Ga₂O₃ and its alloys with In₂O₃ and Al₂O₃ (enabling bandgaps from about 4 eV to >6 eV), will be processed and benchmarked as metal-semiconductor-metal (MSM) detectors. We will investigate possible causes for the slow temporal response and high gain.
3. Conductometric gas sensors based on Ga₂O₃, In₂O₃, SnO₂, and NiO, using well-defined, single-crystalline oxide layers to answer fundamental questions such as bulk- vs. surface conductivity, surface-orientation dependence and the role of local nano-heterojunctions for sensing. Special attention will be given to practical problems, such as cross sensitivity to moisture.

Coordinators

Catherine Dubourdieu (HZB) and and Joachim Würfl (FBH)

Research highlights