Formation of Thin Germanium Dioxide Film with a High-Quality Interface Using a Direct Neutral Beam Oxidation Process

Abstract

A damage-free and low-temperature neutral beam oxidation (NBO) process is used to directly form a thin germanium dioxide (GeO2) film. A GeO2 film with only a small amount of suboxide is formed even at a low substrate temperature of 300 °C because of the extremely low-activation-energy oxidation owing to bombardment with 5-eV-energy oxygen neutral beams. We combined the NBO process with hydrogen radical native oxide removal treatment to form high-quality GeO2 films, and our fabricated Al2O3/GeO2/Ge gate stack has an extremely low interface state density (D it) of less than 1×1011 cm-2 eV-1.

Surface Passivation of Germanium with ALD Al2O3: Impact of Composition and Crystallinity of GeOx Interlayer

“…In the case of Ge, the presence of a considerable amount of poor quality GeO x (x < 2) at the Ge/Al 2 O 3 interface could (i) reduce the amount of negative fixed charge obtainable by the Al 2 O 3 passivation layer, decreasing the field effect, and/or (ii) increase the defect density (compared to better-quality GeO 2 ), deteriorating the chemical passivation. The COCOS results presented (Figure 4) and discussed later on shed more light on this [18,[44][45][46][47][48][49].…”

“…Keeping in mind the different oxidation kinetics for Ge, there could possibly be room for further improvement by optimizing the parameters specifically for Ge. Nevertheless, in terms of Ge surface passivation, both the oxide shift towards higher oxidation states and the increased degree of crystallinity pave the way for the reduced density of surface defects [18,[45][46][47][48][49]. Finally, we studied the impact of increased Ge oxide quality and improved crystallinity obtained with the LT-UHV treatment for the HF + DIW-cleaned sample on ALD Al2O3 surface passivation.…”

Transparent ZnO resistive switching memory fabricated by neutral oxygen beam treatment

“…The concept of this process, in which the kinetic energy of neutral oxygen (O) particles enables the formation of high-quality oxide films at low temperature, is expected to be applicable to the oxidation of various materials. In fact, surface oxidation using the O beam can be applied for the formation of silicon (Si) oxide, [12][13][14][15] germanium oxide, 16,17) gallium arsenide oxide 18) and aluminum oxide. 19) In addition, the formation of a tantalum oxide film and improvement of a ZnO film characteristic were reported to obtain high-quality metallic oxide films as an ionic transport layer, which was applied for the fabrication of RRAM devices, resulting in the typical bipolar resistive switching.…”