Abstract-Surface passivation of high-resistivity silicon (HRS) by amorphous silicon thin-film deposition is demonstrated as a novel technique for establishing HRS as a microwave substrate. Metal-oxide-silicon (MOS) capacitor measurements are used to characterize the silicon surface properties. An increase of the quality factor (Q) of a 10-nH spiral inductor by 40% to = 15 and a 6.5-dB lower attenuation of a coplanar wave guide (CPW) at 17 GHz indicate the beneficial effect of the surface passivation for radio frequency (RF) and microwave applications. Regarding CPW attenuation, a nonpassivated 3000-cm substrate is equivalent to a 70-cm passivated substrate. Surface-passivated HRS, having minimum losses, a high permittivity, and a high thermal conductivity, qualifies as a close-to-ideal radio frequency and microwave substrate.

Solution process of silicon will provide high-speed transistor fabrication with low-cost by, for example, roll-to-roll process. In this paper, a low-temperature process (350 C) is reported for fabrication of high-quality Si devices on a polyimide substrate from doctor-blade coated liquid-Si. With this method, different semiconductor devices have been fabricated, reporting a carrier mobility of 460 cm 2 /V s and 121 cm 2 /V s for electrons and holes, respectively. The devices were peeled off and transferred onto a polyethylene naphthalate foil to achieve flexible devices. CMOS inverters were also fabricated and show full output swing. Printed flexible electronics have received considerable attention because of the low-cost and applications in displays, sensors, and radio-frequency identification (RFID) tags on flexible substrates. Organic semiconductors offer a lowtemperature printing process of TFTs on plastic substrates. 1 However, the carrier mobility and reliability are much inferior in comparison with Si devices. Indium Gallium Zinc Oxide (IGZO), as a metal oxide semiconductor, shows higher electron carrier mobility than that of organic semiconductors, but it is impossible to make both PMOS and NMOS TFTs using the same metal oxide. 2 Transferring of CMOS-SOI chips 3 and amorphous Si (a-Si) transistors on plastics by laser release 4 have been reported. However, the former has cost and technical issues since the limited size of the wafer and pick and place process, and in the latter, the electrical performance is low, although the laser release technique requires less cost. Printing of silicon, however, could provide high carrier mobility 5,6 and at the same time the possibility of fabricating NMOS and PMOS TFTs in the same process on a large area substrate. Silicon can be printed using liquid silicon, 5 which is a mixture of ultraviolet (UV)-irradiated cyclopentasilane (CPS) and a solvent. After forming a-Si by sintering spin-coated liquid-Si at 430 C followed by dehydrogenation, poly-Si TFTs 5 and single-grain Si TFTs 6 have been fabricated with excimer-laser crystallization. Although mobilities of the resultant TFTs are much superior to those of organic TFTs, the dehydrogenation process with a temperature of more than 550 C is not suitable for polymeric substrates. In this paper, we report in the fabrication of singlegrain Si TFTs on a polyimide-coated substrate with a maximum process temperature of 350 C using liquid-Si, which was deposited by doctor-blade coating, which is compatible with a roll-to-roll process. The carrier mobility is 460 cm 2 /V s and 121 cm 2 /V s for electrons and holes, respectively. The devices were peeled off and transferred onto a Polyethylene naphthalate (PEN) foil to achieve flexible devices.As shown in Fig. 1, first, a quasi-plastic substrate is prepared with spin-coating 10-lm-thick polyimide layer on top of a supporting crystalline Si substrate, which is subsequently cured at 400 C. Then, by the l-Czochralski process, 7 small indentations called "grain-filters" (100 nm diamet...

We report high performance single-grain Ge TFTs by μ-Czochralski process. Electron mobilites are 3337cm 2 /Vs with on/off ratio of 10 8 @V DS =0.1V. Hole mobilities are 1719cm 2 /Vs with on/off ratio of 10 8 @V DS =0.05V. The high mobility is due to improved interface property and tensile stress.Introduction:

Solution process of silicon using liquid-Si is attractive for fabrication of high-speed flexible electronics. We have fabricated single-grain Si TFTs on location-controlled Si grains with longpulse excimer laser crystallization of spin-coated liquid Si film. The maximum grain diameter is 3.5µm, and the mobilities for electrons and holes are 423cm 2 /Vs and 118cm 2 /Vs, respectively.

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