Transition metal-nitride-AlGaN layers for electronic applications by sputtering epitax

• Applicants: Professor Dr. Armin Dadgar; Dr. Martin Feneberg
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 462722619

To further enhance GaN power electronics and enable new device structures as well as device designs we will investigate transition metal based nitrides and their alloys as well as their alloys with AlN and GaN. This with the goal to enable true vertical electronics on low cost silicon substrates and lateral enhancement-mode high electron mobility transistors (HEMT) allowing for higher current densities and, therefore more compact device size. In addition we will apply a new growth method, pulsed sputtering epitaxy, which is capable of growing high quality GaN layers at temperatures below 800 °C and thus offers a huge potential for Si CMOS integration of GaN electronics. To identify new materials suited to achieve conducting buffer layers for subsequent GaN epitaxy as well as to achieve new or better functionalities of group-III-N based devices we will investigate transition metal (TM) nitrides also alloyed with AlN and GaN for their potential in group-III-nitride electronic applications. For this we will first study the properties of pure and alloyed group-IIIb -IVb and –Vb-nitrides (Cr, V, Ti, Sc, Nb, Zr, Ta, Hf) with AlN and in some cases also with GaN. Our goal is a database on crystal structure, lattice parameter, electrical and optical properties for a wide range of compositions. In detail the potential will then be investigated for thin films for applications as active layer in electronic devices, e.g. for polarization optimization in HEMTs, novel HEMT structures with, e.g. binary, highly conducting GaN/ScN/GaN channels, as thicker highly conducting film, or as electrically conducting strain engineering layer, enabling true vertical electronic devices on Si substrates. For the latter pure TMN alloys or TMN alloys with AlN are the most promising candidates, while for active layers, apart from binary TMN layers, also alloys with GaN are interesting. Based on the properties of TMNs known to date, we expect that fully vertical devices on Si as well as better HEMT devices are achievable which will primarily result in a further increase in power density of GaN based devices.

• DFG Programme: Priority Programmes
• Subproject of: SPP 2312: Energy Efficient Power Electronics "GaNius"
• Co-Investigator: Professor Dr. Rüdiger Goldhahn