Native oxide removal from Ge surfaces by hydrogen plasma

Abstract

The mechanisms to remove the native oxide layer on Ge(001) surfaces by an in situ hydrogen plasma inside an atomic layer deposition (ALD) reactor has been studied. A strong dependence of the reaction mechanism in the temperature range commonly employed by ALD has been identified through the combined analysis of atomic force microscopy, x-ray photoelectron and Raman spectroscopy. At low temperatures (e.g., 110 °C), the hydrogen plasma removed both Ge and O species from the native GeO2 layer, but also induced surface damage to Ge substrate. At high temperatures (e.g., 330 °C), only O species were removed from the native oxide leaving a nanocrystalline Ge overlayer behind. The thermodynamically unstable nature of hydrogen passivation on Ge resulted in a Ge surface with a high density of dangling bonds. The transition temperature between the two reaction mechanisms was determined to be about 270 °C, allowing to compromise between removing a native oxide layer entirely and hydrogenating the underlying Ge surface without surface damage.

Surface bonding state of germanium via cyclic dry treatments using plasma of hydrogen iodine and pure oxygen gases

“…2). The chemical reaction equation between Ge oxide and hydrogen ions at low temperature is shown as follows: 28…”

Facile synthesis of high-entropy alloy nanoparticles on germanane, Ge nanoparticles and wafers

“…The high-resolution XP spectrum of the Ge 3d region (Fig. S29a, ESI †) showed the presence of Ge 1+ (binding energy at 30.3 eV) and Ge 4+ (binding energy at 32.5 eV) species, 33 indicating that after the removal of the native oxide, the surface Ge undergoes hydrolysis in the water forming Ge-H and Ge-OH on the surface. The generated Ge-H simultaneously reduced the metal ions, resulting in the deposition of the HEA NPs, which is consistent with the SEM images where no obvious local etching was observed.…”