Single electron transistors with hydrogen treatment of ALD SiO₂in nanoscale metal–insulator–metal tunnel junctions

Abstract

Over the past five years, fabrication of metal-insulator-metal (MIM) single electron transistors (SET) featuring atomic layer deposition (ALD) of ultrathin tunnel barrier dielectrics (SiO, AlO) has been reported. However, the performance of fabricated devices was significantly compromised by the presence of native metal oxide and problems associated with the nucleation of ALD dielectrics on metal substrates. To overcome the difficulty of dielectric ALD nucleation on metal substrates, we recently developed a fabrication technique in which the native metal oxide naturally forming in the presence of the ALD oxidant precursor is first used to promote the nucleation of ALD dielectrics, and then is chemically reduced by forming gas anneal (FGA) at temperatures near 400 °C. However, despite the elimination of native oxide, low temperature characterization of the devices fabricated using FGA reveals excess 'switching' noise of a very large magnitude resulting from charged defects within the junctions. It has been previously reported that remote hydrogen plasma (RHP) treatment of SiO thin films effectively eradicates fabrication defects. This work reports a comparative study of Ni-based MIM SET treated with FGA and/or RHP. We show that, using a combination of FGA and RHP treatments, it is possible to obtain MIM junctions free of switching noise and without a detectable contribution of native oxide.

Nanoscale Tunnel Junctions and Metallic Single-Electron Transistors via Shadow Evaporation and In Situ Atomic Layer Deposition of Tunnel Barriers

“…A group at Notre Dame University attempted to fabricate single-electron transistors (SETs) with tunnel barriers prepared by atomic layer deposition (ALD) of Al 2 O 3 , SiO 2 , or SiN x . − ALD is a technique for depositing dielectric films with atomic-scale thickness control through self-limiting adsorption of the source gas. The deposited films have high conformality and uniformity .…”