Y. Shi

Modulating the threshold voltage of oxide nanowire field-effect transistors by a Ga+ ion beam

In this paper, we report a method to change the threshold voltage of SnO2 and In2O3 nanowire transistors by Ga+ ion irradiation. Unlike the results in earlier reports, the threshold voltages of SnO2 and In2O3 nanowire field-effect transistors (FETs) shift in the negative gate voltage direction after Ga+ ion irradiation. Smaller threshold voltages, achieved by Ga+ ion irradiation, are required for high-performance and low-voltage operation. The threshold voltage shift can be attributed to the degradation of surface defects caused by Ga+ ion irradiation. After irradiation, the current on/off ratio declines slightly, but is still close to ∼106. The results indicate that Ga+ ion beam irradiation plays a vital role in improving the performance of oxide nanowire FETs.

Raman scattering studies on the C60 films deposited by ionized cluster beam deposition (ICBD) technique

Abstract Experimental results on Raman-scattering spectra taken at room temperature of C 60 films deposited by ionized cluster beam deposition (ICBD) technique are presented. The Raman spectra show 10 strong Raman lines, consistent with the 10 Raman-allowed (2A g +8H g ) modes predicted for isolated C 60 molecule. A broad feature at high frequency, which varies with acceleration voltage (Va), is also observed and is attributed to amorphous carbon (a-C). The formation and influence of a-C in the ICBD C 60 films are discussed. We think the ICBD technique is very useful in preparing dense and homogeneous pristine C 60 films with stable properties in air.

The Rectification Studies on the P+-Ion Implanted C60/Si Films

Abstract N-type doping of the C60 films deposited on Si substrates has been achieved by 80 keV P+-ion implantation with doses of 2×1014 cm−2 at room temperature. The heterostructures composed of the n-type doped C60 films and n- or p-type Si(111), Si(100) substrates are studied in view of semiconductor heterojunctions. The rectification and other electrical characteristics of the P+-ion implanted n-C60/n-(p-)Si heterostructures are disclosed by the current-voltage (I-V) measurements at room temperature. The n-C60/p-Si heterostructures show stronger rectification than n-C60/n-Si heterostructures and Si(111) substrates are found to be more suitable for forming n-C60/Si heterostructures than Si(100) substrates.