- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Band bending analysis of charge characteristics at GeO <sub/>2</sub> /Ge interface by x-ray photoemission spectroscopy
摘要： Ge complementary metal oxide semiconductor (CMOS) is promising for scaling beyond the Si CMOS due to its higher carrier mobility than Si. Analogue to classical SiO2/Si system in the Si CMOS technology, various interface/bulk charges including interface traps (Qit), fixed surface state charges (Qf), trapped positive charges (Qpt) and negative charges ((Qnt) in GeO2/Ge system are also crucial both for the device performance and reliability. Because small amounts of charges would cause photoemission peak shift characterized by x-ray photoemission spectroscopy (XPS), it offers a feasible way to evaluate various charge densities by measuring the band bending in Ge substrate from Ge 3d core-level energy shift at GeO2/Ge interface. Moreover, photoemission peak shifts as a function of x-ray irradiation time have been widely accepted for characterization of charge trapping phenomena. Here, we report a band bending analysis at GeO2/Ge interface of featuring vital charge characteristics for diverse device applications by XPS. HF-last cleaned Ge surface was verified to tend to be p-type, irrespective of the bulk conductivity. The n-Ge/GeO2 interfaces exhibit a reduction of upward band bending evolution of Ge substrate, while p-type-Ge/GeO2 interfaces indicate a reduction of downward band bending evolution when comparing the different quality GeO2/Ge interfaces. Based on the requirement of surface charge neutrality, such observation has been attributed to a dominated passivation effect to negatively charged interface traps and the positive fixed surface state charges, respectively. Moreover, a time evolution of Ge 3d and O 1s signals reveals a progressive band bending modification at GeO2/Ge interface, clarifying the thermally-grown GeO2 also contains electron traps (Qnt). Ultimately, the four types of charges relying on the GeO2/Ge quality were modeled to correlate with the observed Ge band bending evolution, which would impact both the device operation and reliability.
关键词： band bending,x-ray photoemission spectroscopy,Ge-based electronics,charge characteristics
更新于2025-09-23 15:22:29
-
Growth of InGaN films on hardness-controlled bulk GaN substrates
摘要： We carried out an evaluation of the crystalline quality of bulk GaN substrates and the properties of InGaN ?lms grown on them. The Urbach energy estimated by photothermal de?ection spectroscopy and the tail states near the valence band maximum determined by hard x-ray photoemission spectroscopy were larger for hardness-controlled bulk GaN (hard GaN) than those for conventional bulk GaN (conventional GaN). However, InGaN on hard GaN grows in a step-?ow-like mode, while InGaN grown on conventional GaN exhibits spiral-like growth. The photoluminescence decay at room temperature for InGaN grown on the hard GaN was 470 ps, compared with 50 ps for that grown on the conventional GaN. This can be attributed to the suppression of spiral-like growth due to the resistance to deformation of the hard GaN. These results indicate that substrate hardness is one of the most important factors for III–V nitride growth on the bulk GaN substrate.
关键词： hard x-ray photoemission spectroscopy,photoluminescence,bulk GaN substrates,InGaN films,photothermal de?ection spectroscopy,crystalline quality
更新于2025-09-11 14:15:04
-
Reference Module in Chemistry, Molecular Sciences and Chemical Engineering || Synchrotron-based Spectroscopy In On-Surface Polymerization of Covalent Networks
摘要： Synchrotron radiation is a powerful tool to probe physical properties of materials on the nanoscopic scale. It can provide a chemical fingerprint of a nanomaterial with unrivalled resolution, it can measure the geometric structure down to thousands of a nanometer with not only elemental sensitivity but also chemical sensitivity, and it can study charge transfer dynamics in the sub-nanosecond regime. Within this article the application of synchrotron radiation to studying on-surface catalysis, to the view of forming two-dimensional covalent networks, will be explored.
关键词： covalent networks,on-surface polymerization,Normal Incidence X-ray Standing Waves,Synchrotron radiation,X-ray Photoemission Spectroscopy,Near Edge X-ray Absorption Fine Structure
更新于2025-09-10 09:29:36
-
Electrical properties of α-Ir <sub/>2</sub> O <sub/>3</sub> /α-Ga <sub/>2</sub> O <sub/>3</sub> pn heterojunction diode and band alignment of the heterostructure
摘要： Corundum-structured iridium oxide (a-Ir2O3), showing p-type conductivity, is a strong candidate to form high-quality pn heterojunctions with a-Ga2O3. We fabricated a-Ir2O3/a-Ga2O3 pn heterojunction diodes and they showed well-defined rectifying current-voltage (I-V) characteristics with the turn-on voltage of about 2.0 V. The band alignment at the a-Ir2O3/a-Ga2O3 interface was investigated by X-ray photoemission spectroscopy, revealing a staggered-gap (type-II) with the valence- and conduction-band offsets of 3.34 eV and 1.04 eV, respectively. The total barrier height for electrons was about 2.4 eV, which reasonably agreed with the turn-on voltage in the I-V characteristics. This means that electrons are mainly attributed to electrical conduction around the turn-on voltage.
关键词： pn heterojunction,a-Ir2O3,X-ray photoemission spectroscopy,a-Ga2O3,band alignment
更新于2025-09-09 09:28:46
-
Study of the Interface of the Early Stages of Growth under Quasi-Equilibrium Conditions of ZnO on Graphene/Cu and Graphite
摘要： The study of the early stages of growth of ZnO on graphene supported on Cu and on highly oriented pyrolytic graphite by means of reactive thermal evaporation of metallic Zn at room temperature is presented. This growth method allows to go in depth in the study of the fundamental interaction between ZnO and graphene at the interface in quasi-equilibrium conditions. Quantitative, chemical, and morphological analysis is performed using photoemission spectroscopy, atomic force, and scanning microscopies as experimental characterization techniques and factor analysis and inelastic peak shape analysis as modeling techniques. The growth of ZnO on a highly oriented pyrolytic graphite substrate is also studied using the same growth method for comparison. The results show that, in spite that the first atomic layer of both substrates is identical, the growth kinetics and morphology of the deposits are completely different. A model for the kinetics of the growth of ZnO on both substrates is proposed.
关键词： X-ray photoemission spectroscopy,early stages of growth,ZnO/graphene interfaces,atomic force microscopy,nanostructured ZnO thin films
更新于2025-09-04 15:30:14