Growth Dynamics, Fabrication and Operational Stability of Organic Field-Effect Transistors Based on SnCl2Pc, VOPc and CuPc Molecules
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This thesis presents a systematic study on the growth mechanism, growth dynamics of organic thin films and device performances of organic unipolar and ambipolar field-effect transistors based on phthacyanine molecules. The complete thesis work has been organized into eight chapters. The present chapter, i.e., Chapter 1 introduced a brief account of the organic semiconductors, particularly small molecule based SnCl2Pc, VOPc, CuPc molecules. This chapter also included brief discussion on the study of growth kinetics of thin films, charge transport, electrical parameters of OFETs, and its bias stress stability. Chapter 2 provides a brief description of the experimental techniques used for the present work along with the working principles of some characterization tools. In Chapter 3, we present the results the evolution of surface morphology and scaling behavior of non-planar SnCl2Pc thin films grown on Si(100) and glass substrates. Our results imply the superiority of glass substrate over the Si substrate for the growth of device quality SnCl2Pc thin film. The systematic study of substrate dependent growth behavior and possible growth model is described elaborately in this chapter. In Chapter 4, we present the systematic study of the surface evolution and growth dynamics of non-planar VOPc molecular thin film on SiO2 and ITO-glass substrate, substrate temperature dependent growth behavior and particularly provide some insights on the role of molecular-substrate interface. It includes discussion on the substrate induced growth scenario from the AFM, height-height correlation function (HHCF) and two dimensional fast Fourier transform (2D FFT) analyses. Chapter 5 provides a quantitative analysis of the electrical performances and stability of vacuum-deposited thin film based n-channel organic field-effect transistors with SnCl2Pc in top contact bottom gate configuration using Ag source/drain electrodes and PMMA/Al2O3 as a bilayer gate dielectric as well as SiO2 gate dielectric.
Supervisor: P. K. Giri