We have fabricated high-performance enhancement and depletion mode (E-and D-mode) top-gate metal-insulator-semiconductor field-effect transistors (T-G MISFETs) using two kinds of CdS nanobelts (NBs), labeled as NB A and NB B, respectively. High-k HfO 2 dielectric is used as the insulator layer. The thicknesses of NBs A and B are about 60 and 180 nm, respectively. The threshold voltage and subthreshold swing of the CdS NB A T-G MISFET are about 0.15 V and 62 mV/dec, respectively. The on/off ratio is about 6 Â 10 4 , which is the best result for E-mode CdS nanoFETs reported so far. The threshold voltage, on/off ratio and peak transconductance of the CdS NW B T-G MISFET are about À3.4 V, 2 Â 10 9 , and 11 mS, respectively. The on/off ratio, to the best of our knowledge, is the highest reported for nanoFETs so far. Both of the two kinds of T-G MISFETs have quite small hysteresis in their transfer characteristics. The mechanisms for the different gate transfer characteristics are discussed. Corresponding Si back-gate CdS NB MISFETs each with a 600 nm SiO 2 film as the insulator layer are also measured for comparison.

Enhancement-mode (E-mode) metal-semiconductor field-effect transistors (MESFETs) based on single nanowires (NWs) were reported. The single NW used is n-CdS NW. Source-drain channel of the nano-MESFET is pinched off by the top surrounding Schottky gate at zero bias. When Schottky gate voltage (VG) changes from 0to0.25V, the source-drain current increases exponentially with VG, and an on/off current ratio of 5×103 is obtained. The maximum transconductance is 14.6nA∕V, and the gate leakage current is lower than source-drain current by more than two orders of magnitude. Their results suggest a way of fabricating E-mode nano-field-effect transistors.

Single-crystalline Zn 3 P 2 nanowires (NWs) have been synthesized on silicon (Si) substrates via a vapor phase transport method. Zn (99.99%) powder and InP (99.99%) fragments were used as the sources, and 10 nm thick thermal evaporated gold (Au) film was used as the catalyst. The as-prepared Zn 3 P 2 NWs have diameters of 100-200 nm and lengths of more than 10 mm. Single NW metalinsulator-semiconductor field-effect transistors (MISFETs) based on Zn 3 P 2 NWs were fabricated. Electrical transport measurements show that the as-grown Zn 3 P 2 NWs are of p-type. The hole concentrations and mobilities of the p-type Zn 3 P 2 NWs are about 5.6 Â 10 16 cm À3 and 42.5 cm 2 V À1 s À1 , respectively. The on-off ratio of the MISFET is about 4 Â 10 4 , and its threshold voltage and transconductance are 2.5 V and 35 nS, respectively. These parameters indicate that the p-type Zn 3 P 2 NWs are of high quality, and may have potential applications in nanoscale electronic and optoelectronic devices.