Search

We have investigated the core levels and the valence band of (Ge2Sb2Te5)1-x(In3Sb1Te2)x quaternary phase system (IGST) by means of x-ray photoelectron spectroscopy. A systematic shift of Sb 3d and Ge 2p core-level peaks toward lower binding energies side was observed with increasing indium amount, whereas the In 3d and Te 3d core peaks showed less change. The Sb 3d and Ge 2p core-level shift is attributed to an increase in the electronic charge of p-electrons dependent of indium amount. The valence band spectra show a distinct change in the sp configuration with indium concentration change. The change in the local bonding as the indium amount increase has a profound impact on both local atomic arrangement and amorphous-to-crystalline transformation temperature. The difference in the photoemission spectra have been discussed according to a simple structural model suggesting that the Na site in IGST can be occupied by Te, Sb, In, and vacancy, whereas in GST it is occupied only by Te. [ABSTRACT FROM AUTHOR]

Short channel device performance of deep-submicron gate length oxide thin film transistor (TFT) with amorphous InGaZnO (a-IGZO) active semiconductor is presented. Remarkable electrical properties of short channel oxide TFT were achieved utilizing crucial structure and material optimization such as self aligned gate structure with homo junction, multi-channel with rounded corners, and high-κ gate dielectric. It was found that various device performance parameters of short channel-oxide TFTs were significantly influenced by materials, processes, and structural geometry, which should be more carefully designed. [ABSTRACT FROM AUTHOR]

To achieve high-mobility and high-reliability oxide thin film transistors (TFTs), ZnON has been investigated following an anion control strategy based on the substitution of oxygen with nitrogen in ZnO. However, as nitrogen possesses, compared to oxygen, a low reactivity with Zn, the chemical composition of ZnON changes easily, causing in turn a degradation of both the performance and the stability. Here, we have solved the issues of long-time stability and composition nonuniformity while maintaining a high channel mobility by adopting the argon plasma process, which can delay the reaction of oxygen with Zn-O-N; as a result, owing to the formation of very fine nano-crystalline structure in stable glassy phase without changes in the chemical composition, the material properties and stability under e-radiation have significantly improved. In particular, the channel mobility of the ZnON TFTs extracted from the pulsed IV method was measured to be 138 cm²/V s. [ABSTRACT FROM AUTHOR]

We introduce single-phase In–Ge–Sb–Te (IGST) quaternary thin film (fcc structure when crystallized) deposited by cosputtering from Ge2Sb2Te5(GST) and In3Sb1Te2 targets. This film, compared with the GST ternary system, provides a significant increase of amorphous-to-crystalline transformation temperature. High-resolution x-ray photoelectron spectroscopy (HRXPS) revealed that, with increasing In amounts, the Sb 4d and Ge 3d core peaks shift toward lower binding energies (BEs), with negligible changes in spectral linewidths, whereas the In 4d and Te 4d core peaks show insignificant changes in BEs. HRXPS interpretation suggests that the Na site in IGST can be occupied by Te, Sb, In, and vacancy, whereas in GST it is occupied only by Te. [ABSTRACT FROM AUTHOR]

The present paper reports the energy loss near-edge structure (ELNES) study of monoclinic HfO2 (m-HfO2) and tantalum doped m-HfO2 (Ta0.1Hf0.9O2) thin films prepared by radio frequency magnetron co-sputtering method. A change in the O K-ELNES spectra was observed as the amount of dopant increases. In order to precise the common features and the differences as a function of Ta defect nature (substitutional or interstitial) in HfO2, the O K-ELNES were commented with respect to density functional theory calculations implemented in Vienna ab initio simulation package code. The calculated Ta doped HfO2 band structure showed that substitutional tantalum is the dominant defect and the spectral differences between doped and non-doped HfO2 are mainly originated from the change in the local cation distribution around the oxygen atoms. [ABSTRACT FROM AUTHOR]