96 research outputs found
Study of electron traps associated with oxygen superlattices in n‐type silicon
status: publishe
TiO2/HfO2 bi-layer gate stacks grown by atomic layer deposition for germanium-based metal-oxide-semiconductor devices using GeOxNy passivation layer
Effective reduction of fixed charge densities in germanium based metal-oxide-semiconductor devices
Effective Electrical Passivation of Ge(100) for HfO2 Gate Dielectric Layers Using O2 Plasma
Nucleation Mechanism during WS2 Plasma Enhanced Atomic Layer Deposition on Amorphous Al2O3 and Sapphire Substrates
The structure, crystallinity and properties of as-deposited two-dimensional (2D) transition metal dichalcogenides are determined by nucleation mechanisms in the deposition process. 2D materials grown by atomic layer deposition (ALD) in absence of a template, are polycrystalline or amorphous. Little is known about their nucleation mechanisms. Therefore, we investigate the nucleation behavior of WS2 during plasma enhanced ALD from WF6, H2 plasma and H2S at 300 °C on amorphous ALD Al2O3 starting surface and on monocrystalline, bulk sapphire. Preferential interaction of the precursors with the Al2O3 starting surface promotes fast closure of the WS2 layer. The WS2 layers are fully continuous at WS2 content corresponding to only 1.2 WS2 monolayers. On amorphous Al2O3, (0002) textured and polycrystalline WS2 layers form with grain size of 5 nm to 20 nm due to high nucleation density (~1014 nuclei/cm2). The WS2 growth mode changes from 2D (layer-by-layer) growth on the initial Al2O3 surface to three-dimensional (Volmer-Weber) growth after WS2 layer closure. Further growth proceeds from both WS2 basal planes in register with the underlying WS2 grain, and from or over grain boundaries of the underlying WS2 layer with different in-plane orientation. In contrast, on monocrystalline sapphire, WS2 crystal grains can locally align along a preferred in-plane orientation. Epitaxial seeding occurs locally albeit a large portion of crystals remain randomly oriented, presumably due to the low deposition temperature. The WS2 sheet resistance is 168 MΩµm suggesting that charge transport in the WS2 layers is limited by grain boundaries.status: publishe
Enhanced initial growth of atomic-layer-deposited metal oxides on hydrogen-terminated silicon
A route is presented for activation of hydrogen-terminated Si(100) prior to atomic layer deposition. It is based on our discovery from in situ infrared spectroscopy that organometallic precursors can effectively initiate oxide growth. Narrow nuclear resonance profiling and Rutherford backscattering spectrometry show that surface functionalization by pre-exposure to 108 Langmuir trimethylaluminum at 300 °C leads to enhanced nucleation and to nearly linear growth kinetics of the high-permittivity gate dielectrics aluminum oxide and hafnium oxide
Effective reduction of fixed charge densities in germanium based metal-oxide-semiconductor devices
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