The characteristics of Al/InP Schottky diode without and with (NH 4 ) 2 S treatment (Al/S-InP) and corresponding MOSFET with atomic layer deposited TiO 2 /Al 2 O 3 stacked gate oxides were investigated. The Schottky barrier height (I Bp ) of Al/InP with (NH 4 ) 2 S treatment is improved from the removal of native oxides. For Al/S-InP Schottky barrier MOSFET with TiO 2 /Al 2 O 3 gate oxides, good drain currentvoltage and sub-threshold characteristics were obtained. The channel mobility and transconductance can reach 202 mm 2 /Vs and 4.45 × 10 -7 S/μm at V DS = 1 V. Keywords-Schottky barrier, ALD, Al 2 O 3 , TiO 2 , InP, MOSFET I. INTRODUCTION ecently, III-V compound semiconductor MOSFETs have attracted strong attention as the scaling of Si CMOS technology beyond the 22 nm node for their higher electron mobility than Si-based counterparts [1]. For high performance III-V channel MOSFETs, the source/drain (S/D) region with a low resistance is remained as one challenge because of the limited dopant solubility and activation rate [2]. The metal Schottky S/D structure is a promising solution due to the low resistance and low temperature process.The gate dielectric with low interface state density (D it ), and good thermal stability is also essential for high performance MOSFET. Many high-k dielectrics are currently being explored on InP. TiO 2 has a relatively high dielectric constant (k value 35-100 depending on the growth method) and high transconductance MOSFET with TiO 2 gate oxide is expected. However, the high thermionic emission of low band-gap TiO 2 (3.5 eV) needs a high band-gap, for example Al 2 O 3 (9 eV) stacked on it. Films with precise thickness can be prepared by atomic layer deposition (ALD), in which selflimiting precursors are sequentially deposited [3]. ALD offers higher quality thin film on atomic scale over conventional MOCVD (metal-organic chemical vapor deposition). In addition, ALD-Al 2 O 3 on III-V compound can improve the interface quality by the self-cleaning reaction on native oxides [4], which is the main contribution to high interface state density (D it ) [5]. High D it will cause the Fermi-level pinning at the interfaces of Schottky S/D and gate oxide on III-V

High quality nano-scaled fluorine and nitrogen co-doped anatase phase TiO2 can be obtained from the conversion of ammonium oxotrifluorotitanate by thermal treatment. The photocatalytic activity of TiO2 treated at 800oC shows the highest photocatalytic activity and is about 1.3 times of commercial P-25. The heterojunctions of ZnSe/TiO2 and ZnS/TiO2 prepared by metal organic vapor phase epitaxy shows 2.0 and 1.5 times the photocatalytic activities of commercial P-25. In this study, nano-scaled TiO2, ZnSe/TiO2 and ZnS/TiO2 heterojunctions show one to one correspondence between carrier lifetime and photocatalytic activity.

ZnO nanotips were synthesized on a sputtered ZnO buffer layer/ITO/glass by aqueous solution deposition with precursors of zinc nitrate and ammonia. Growth direction of ZnO nanotips can be controlled by the thickness of sputtered ZnO buffer layer. The average height of 13 μm was obtained at 70 °C for 24 hr and the diameter of ZnO nanotips was ranged from 60 nm to 100 nm.

ZnO nanotips were synthesized on a sputtered ZnO buffer layer/ITO/glass by aqueous solution deposition with precursors of zinc nitrate and ammonia. The density of ZnO nanotips can be controlled by the thickness of sputtered ZnO buffer layer. The average height of 13 μm was obtained at 70°C for 24 hr and the diameter of ZnO nanotips was ranged from 60 nm to 100 nm. By thermal annealing at 300 oC in N2, the ZnO quality can be much improved and strong Micro-PL UV emission (380 nm) and lower defect emission (520 nm) of visible region are obtained. After thermal annealing at 300 °C in O2, both emissions are much improved.

The high Dit is the major problem of III-V compound semiconductor MOSFET, which causes the pinning of the surface Fermi level near the middle of the energy gap. The GaAs with (NH4)2Sx treatment (S-GaAs) can remove the native oxides on GaAs and prevent it from oxidizing. The electrical characteristics of fluorinated polycrystalline TiO2 films deposited on p-type(100) S-GaAs were investigated. The fluorine from liquid phase deposition solution can passivate the grain boundary of polycrystalline TiO2 prepared by MOCVD. The leakage current through the grain boundaries was suppressed. The leakage current of MOCVD-TiO2/S-GaAs can be improved from 6.8 x 10-6 and 0.2 A/cm2 to 3.41 x 10-7 and 1.13 x 10-6A/cm2 under positive and negative electric fields at 1.5 MV/cm, respectively. Dit and k can be improved from 1.44 x 1012 cm-2eV-1 to 4.6 x 1011 cm-2eV-1 and 52 to 65, respectively. The effective oxide charges can be improved from 2.5 x 1012 C/cm-2 to 9.3 x 1011 C/cm-2.