Surface passivation of germanium nanowires using Al₂O₃and HfO₂deposited via atomic layer deposition technique

Abstract

We have successfully passivated the surface of germanium nanowires (Ge NWs) using aluminum oxide (Al2O3) and hafnium oxide (HfO2). The atomic layer deposition (ALD) technique was used to deposit Al2O3 and HfO2. We observed an excellent interface between the nanowire surface and Al2O3 and exceptional uniformity of Al2O3 along the length of the nanowire. In the case of nanowires coated with HfO2, we found that a local crystallization of HfO2 may cause defects on the nanowire surface. We have fabricated devices using Ge NWs coated with ultra-thin Al2O3. The current through the nanowire increased after sequential annealing at 400 °C under a forming gas atmosphere. The current increase is ascribed to the diffusion of germanium into Al2O3 that affects the barrier thickness between the metal and the Al2O3/Ge NW. The ultra-thin Al2O3 serves to eliminate charge trapping and protect the germanium surface from ambient molecules and therefore alleviate hysteresis.

Tunable conduction type of solution-processed germanium nanoparticle based field effect transistors and their inverter integration

“…Recently, the same approach was used to passivate germanium nanowires grown on gold nanoparticles. 29 This study shows that thin Al 2 O 3 can eliminate surface charge trapping and protect the germanium surface from the adsorption of ambient molecules, resulting in a current increase. More recently, the same approach for ZnO nanocrystals has been studied.…”

Ge-Core/a-Si-Shell Nanowire-Based Field-Effect Transistor for Sensitive Terahertz Detection

“…Therefore, additional artificial surface passivation of Ge NWs is required. Organic layers such as alkanethiols [28], aqueous halide solutions [29], and dielectric layers such as aluminum oxide (Al 2 O 3 ) and hafnium(IV) oxide (HfO 2 ) [30] can be used to passivate the Ge NW surface. The current method for surface passivation includes use of an a-Si shell deposited by chemical vapor deposition (CVD).…”

Ge/Si core/shell nanowires with controlled low temperature grown Si shell thickness

“…Gold (Au) is most commonly used as a catalyst. In our labratory, we have successfully prepared small (12 nm) and uniform Si nanowires , and Ge nanowires (3 nm) at low temperatures and studied various effects of surface and orientation of substrates on the growth of Ge nanowires . We also have investigated the microscopic structure of Ge nanowires grown below eutectic temperature of AuGe .…”