Electron energy band alignment at interfaces of (100)Ge with rare-earth oxide insulators

Abstract

Energy diagrams of interfaces between (100)Ge and several rare-earth oxide insulators deposited from a molecular beam are determined using a combination of internal photoemission and photoconductivity measurements. For the wide band gap (5.9eV) oxides Gd2O3 and LaHfOx, the band alignment at the interface is found to be close to that of HfO2 and is characterized by conduction/valence band offsets of ∼2∕∼3eV. In contrast, CeO2 which has a much narrower band gap (3.3eV) does not provide a band alignment diagram corresponding to sufficient insulation.

(DS&T Thomas D. Callinan Award Presentation) Role of Hydrogen in Dielectrics for Electronics and Optoelectronics Devices

“…Higher initial interface trap density was observed for nitrided devices compared to non-nitrided devices because of presence of nitrogen at the interface that facilitated the formation of Ge-Hf bonds [47] that further degraded the interfacial properties. As mentioned earlier, no measurable density of dangling bonds of the germanium surface atoms is found in Ge/high-k structure [7], release of atomic hydrogen from the dangling bond sites is, therefore, minimal. For nonnitrided devices, on the other hand, D it generation increases linearly initially with stress time (10s) because increase in stress temperature increases D it generation at early stress time.…”

“…This makes the Ge dangling bonds negatively charged and they become insensitive to electron spin resonance measurement. Therefore, Afanas'ev et al (7) through electron spin resonance measurement found no evidence of Ge dangling bonds at the Ge/HfO 2 interface, as electron spin resonance is only sensitive to neutral dangling bonds. In Ge devices, however, interstitial hydrogen plays a significant role (8).…”

Effects of electric field in band alignment measurements using photoelectron spectroscopy

“…[5] In the measurement of band alignments, a single or combination of several techniques such as electrical conductivity, Kelvin probes or internal photoemission measurements can be used. [6][7][8] A common, nondestructive and indirect method is to examine the interface core-level binding energies using XPS. Measurement of the valence band offset (VBO) can, in principle, be accurately achieved using the method introduced by Kraut et al [9,10] The method measures the difference between the core level (E CL ) and the valence band maximum (VBM) (E V ) of the two bulk materials and the separation of the core levels at the interface upon contact.…”

(Electronics & Photonics Division Award Presentation) Si-SiO2 Interface to High-K-Ge/III-V Interface: Passivation and Reliability

“…Afanas'ev et al (59) found no such center of Ge dangling bonds at the Ge-HfO 2 interface. The dominant contributors to interface traps were found to be the defect centers in the dielectric layer close to the interface.…”