6PB10 6PBll Determination of t h e Work Function of t h e CO Thin

Films by Using ?-FIB System'

Hyun J. Oh, Jung W. Hyun, Ymnn C. Lim, Sung S. Kim, Tae W. Kim, Eun H. Choi, and Senng 0. Kang

Department of Eleetmphysies, Kwongwwn Univers 447-1, Wolgye-dong, Nowon-gu, Seoul 139-701, Korea

The Physical properties of the metal-semiconductor heteroint- erfaces have received much attention for many years because of a desire to develop fabrication technology for high-speed electron devices. Recently, the growth of magnetic thin films on com- pound semiconductor substrates has been particularly attractive from both the scientific and the technological points of view in connection with spintronics. Investigations of the secondary elec- tron emission coefficient y and the work function of Co thin films grown on GaAs substrate are very important for understanding the electronic properties of the Co/GaAs heterostructures. CO thin films on the GaAs(100) substrates were grown at room tem- perature by using the ion beamassisted deposition. The secondary electron emission coefficient y measurements were carried out us- ing a home made -,-Focused Ion Beam system, and the He, Ne, AI, Xe gases used as ion sources. The work function of the CO thin films can be determined from the dependences of the 7 values on the type of incident ion and on the acceleration voltage by using Auger neutralization theory. These results provide important in- formation,on the electronic properties of CO thin films grown on GaAs(100) substrates at mom temperature.

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Microcrystalline Silicon Growth Using a Inductive .Coupled Plasma CVD on Plastic Substrate'

D.Y. Kim, C.K. Sm, M.S. Sim, C.H. Kim, S.J. Bae and Junsin Yi

School of Electricd and computer Engineering, Sungkyunkwnn Uniu. 300 Chunehun-dong, Jongon-gu, Kpnggt-do, Suwon,

440- 746, K o e o

Recently, the plastic materials are very useful as the sutstrate of the flexible, light and portable electronics. Although the plas tic substrates have many advantages such as thin film solar cell, thin film transistor and thin film sensors, its application has a difficulty of the limitation of temperature, surface hardness, and corrosion resistance on the acid or alkali. In general, hydrogenated amorphous silicon .(a-Si:H) films ace found in a broad range of electronjc devices such as radiation detectors, photovoltaic (PV) devices, thin film transistors (TFTs), display devices, and mem ory device applications. However, a-Si:H detectors and TFTs show some limitations because of their low carrier mobility. A-SiH solar cells have exhibited problems on stability of conversion efficiency. These problems regarding a-Si:H films can be solved by replacing a-Si:H with microcrystalline silicon (p-Si) film. The goal of our re- search is to determine the best process conditions for the growth of pc-Si on a plastic substrate The films of F-Si with thickness in.the range 20-120- were deposited in inductive coupled plasma chem- ical vapor deposition (ICP-CVD) system from mixture of diluted silane (SiHa 20% in He) and H1 at low temperature of 100". Poly- carbonate (PC) substrate (lmmthickness) 50x50 nun2 wasused as substrate. PC substrate has a higher heat resid of 130" than other plastic substrate and no problem to the alkali liquid. To verify the growth of pc-Si film using an ICP-CVD, we investigated crystalline seeding layer on the plastic substrate and the optimized growth pa- rameters of ICP. They were ultrasonically cleaned in methanol, D.I. water rimed, and nitrogen-gas blown dry. The investigated process parameters for the Si film growth include: plasma ignition condi- tions, rf power, input gas ratio, process pressure, with or without carrier gas. An atomic force microscope (AFM) was employed for the surface morphology study and growth mechanism. An argon laser drive-Ramm spectroscopy (JobinYvon /T64000, power=4LKJ mW) was employed to determine the degree of crystallization and crystallized volume fraction of the W-Si film.

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