ICMCTF2012 Session C2-1/F4-1: Thin Films for Photovoltaics and Active Devices: Synthesis and Characterization

Monday, April 23, 2012 10:00 AM in Room Tiki Pavilion

Monday Morning

Start	Invited?	Item
10:00 AM		C2-1/F4-1-1 The Degradation of Ti_xN_1-x/HfO₂ p-channel MOSFETs under Hot Carrier Stress Jyun-Yu Tsai (National Sun Yat-Sen University, Taiwan) This work investigates the hot carrier (HC) effect in HfO2/Ti_xN_1-x p-channel metal oxide semiconductor field-effect transistors (p-MOSFETs). Generally, the sub-threshold swing (S.S) should increase during HC stress, since the interface states near drain will be generated under high electric field due to drain voltage (V_D). However, the experimental data exhibits the S.S decreases under HC stress and the degradation level is dependent on the concentration of nitrogen in stack gate (Ti_XN_1-X). Besides, the reduction of threshold voltage (V_th) illustrates the electrons trap in HfO₂ layer under HC stress. This behavior could be attributed to increase in the entire capacitance due to electron trapping in HfO₂ bulk, improving S.S. Furthermore, the C-V measurement with high and low frequency could detect the defects which approach HfO₂ layer, evidencing the trapping pheromone in this work.
10:20 AM		C2-1/F4-1-2 Investigation of Random Telegraph Signal with High-K/Metal Gate MOSFETs Ching-En Chen (National Chiao Tung University, Taiwan) A novel method, called random telegraphy signal (RTS), was constructed to characterize the gate oxide quality and reliability of metal-oxide-semiconductor field-effect-transistors (MOSFETs). With the aggressive scaling of device size, drain current RTS (Id RTS) become a critical role in carrier transport of MOSFETs. Besides, RTS in gate leakage current (Ig RTS) was denoted as the other new method to understand property of gate oxide. Recently, the study of RTS has also been made in MOSFETs with high dielectric constant and metal gate (high-k/metal gate). However, the RTS in high-k/metal gate MOSFETs, which is related to hot carrier stress (HCS), has not previously been studied yet. This paper investigates the mechanism of HCS in high-k/metal gate MOSFETs and provides a fundamental physical model.
10:40 AM		C2-1/F4-1-3 Enhancement of Resistive Switching Characteristics in SiO₂-based RRAM by High Temperature Forming Process Yu-Ting Chen (National Sun Yat-Sen University, Taiwan) Forming process with current compliance (soft break-down) is necessary to activate the resistive switching behavior for most of the resistance random access memory (ReRAM). Due to the rich oxygen ions among SiO₂ film, the amount of mobile oxygen ions induced from forming process would exceed the reserving ability of TiN oxygen reservoir as the thickness of SiO₂ films are too thick. The exceeding mobile oxygen ions will recombine with the oxygen vacancies in the SiO₂ film near the TiN/SiO₂ interface and result in forming fail. Through executing high temperature forming process (HTF), it improves the forming process by enhancing the amount of mobile oxygen ions being drove into TiN electrode. Furthermore, the increased mobile oxygen ions can extra repair the conductive filament and reach lower off-current during the reset process that has undergone HTF for activation.
11:00 AM		C2-1/F4-1-4 The Impact of Strain on Gate-Induced Floating Body Effect for PD SOI p-MOSFETs Wen-Hung Lo, Ting-Chang Chang, Chih-Hao Dai (NSYSU, Taiwan) This work studies the influence of gate induced-floating body effect (GIFBE) on negative bias temperature instability (NBTI) in strained partial depleted silicon-on-insulator p-type metal-oxide-semiconductor field effect transistors (PD SOI p-MOSFETs). The experimental results indicate GIFBE causes a reduction in the electrical oxide field, leading to a better NBTI reliability under FB operation. The electron accumulation in the FB can be partially attributed to the electrons tunneling from the process-induced partial n+ poly gate. However, based on different operation conditions, we found the dominant origin of electrons was strongly dependent on holes in the inversion layer under source/drain grounding. This suggests that the mechanism of GIFBE at higher voltages is dominated by our proposed anode electron injection (AEI) model. Moreover, based on this new model, the mechanical compressive strained operation was further introduced to the SOI p-MOSFET. It was found that the strained device under FB operation exhibits a much less NBTI degradation. This behavior can be attributed to the fact that more electrons accumulation induced by strain effect reduces the electric oxide field during NBTI stress.
11:20 AM	Invited	C2-1/F4-1-5 Plasma deposited ZnO layers for thin film photovoltaics: synthesis, characterization and growth mechanism Mariadriana Creatore (Eindhoven University of Technology, Netherlands) Due to their wide band gap, transparent conductive oxides ( TCOs) exhibit a high transparency in the solar spectral range. Therefore, they are used as transparent electrodes in many applications, e.g. in flat panel displays, architectural and automotive glazing, solar thermal applications and thin film solar cells, either (amorphous/micro-crystalline and poly-crystalline) silicon- or non-silicon based (e.g. CIGS). In this contribution, the investigation on low pressure plasma-enhanced chemical vapor deposition (PE-CVD) of poly-crystalline (Al-doped) zinc oxide layers serving as TCOs in thin film solar cells, is addressed. An argon- fed expanding thermal plasma where the deposition precursors (diethylzinc, trimethylaluminum and oxygen) are fed in the downstream region is used for the deposition of Al- doped ZnO. The presented studies will highlight the impact of specific plasma and process parameters on the ZnO:Al nucleation phase, grain development (in terms of crystallographic orientation and size) and morphological and electrical properties, coupled to specific demands in thin film solar cell technology, i.e. in terms of band gap, conductivity and morphology/texturing. In particular, selected insights will be presented in research areas, where a multi-diagnostic approach is adopted in order to investigate: - The control on the gradient in resistivity of the ZnO:Al layer as function of its thickness, as supported by the correlation between texturing, grain size development and carrier mobility; - The impact of the surface energy of a thin intrinsic ZnO layer on the development of the morphological and electrical properties of the ZnO:Al layer; - The influence of the annealing procedure (i.e. solid phase crystallization) on ZnO:Al/amorphous silicon (a-Si:H) stacks on the TCO conductivity and on the crystallization kinetics towards poly-crystalline silicon formation, for thin film poly-Si solar cells.