SOLUTION PROCESSING OF LOW VOLTAGE, LOW TEMPERATURE, SUSTAINABLE, TRANSPARENT OXIDE FIELD-EFFECT TRANSISTORS

solution processing;oxide;field-effect transistors;low voltage;low temperature;ion-incorporated alumina;zinc oxide;zinc tin oxide;Materials Science & Engineering

Liu, YuArmitage, N. Peter ;

Johns Hopkins University

关键词: solution processing;    oxide;    field-effect transistors;    low voltage;    low temperature;    ion-incorporated alumina;    zinc oxide;    zinc tin oxide;    Materials Science & Engineering;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/40674/LIU-DISSERTATION-2015.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

Solution processing is a promising method for manufacturing large-area, low-cost electronic devices. Oxide is a group of earth abundant, environmental friendly materials with tunable energy bands and charge carrier concentration, so they are widely applied as semiconductors, dielectrics, and conductors in flat panel displays, photovoltaics, lighting, sensors, and radio-frequency identification tags (RFIDs). Oxide thin films can be solution processed with good control of stoichiometry and microstructures with proper design of precursor solution, deposition condition, and post-annealing procedures. In this thesis, oxide dielectric and semiconductor thin films were fabricated and analyzed. Ion incorporation in alumina dielectrics offers exceptionally high capacitance and thus significantly reduces operation voltage of field-effect transistors (FETs). Alumina capacitance can be manipulated by incorporation of alkali metal ions with different bond strength with oxygen, including potassium, sodium, and lithium. Ion-incorporated aluminas capacitors exhibited a strong frequency dependence of capacitance with a possible electric double layer capacitor (EDLC) behavior. To investigate the effect of alkali metal ion on the detailed alumina capacitance and AC conductivity response, the frequency, temperature, and thickness dependences of alumina capacitance were determined. Distinct transistor stability behavior under pulsed gate bias stress observed among ZTO FETs with ion-incorporated aluminas and plain aluminum oxide gate dielectrics. Distinct bias stress induced change in drain current, threshold voltage, and saturation field-effect mobility of ion-incorporated aluminas and plain alumina based FETs reflects different interfacial charge trapping behavior and suggests possible formation of defect states. Solution processing of semiconductor materials on large area flexible substrates usually involves a trade-off among facile charge transport, high-capacitance/low voltage transistor gates, and low processing temperature. In this research, we fabricated all-oxide field-effect transistors using sol-gel solution processing techniques at 200-250 °C temperatures. A simplified aqueous precursor solution preparation method was discovered to prepare ZnO as semiconducting layer. ZnO FETs with SiO2 gate dielectric fabricated at 200 °C exhibited a saturation field-effect mobility of 0.7 cm2•V-1•s-1 and a typical on/off current ratio on the order of 104. In addition, combustion precursors were synthesized to fabricate a high capacitance sodium ion-incorporated alumina (SA) dielectric with annealing below 250 °C. With the combustion-processed SA gate dielectric, ZnO FETs were fabricated and successfully operated at 5 V.