Optoelectronic Properties on Indium-Magnesium-Oxide (MIO) Thin Film Transistors and Improvement by Using Cap Layer and Buffer Layer

  • 林 承緯

Student thesis: Master's Thesis


In this thesis we utilize co-sputter system to prepare amorphous indium magnesium oxide (MIO) thin film; moreover thin film transistors (TFTs) and UV phototransistors are fabricated and analyzed First we deposit a-MIO thin film on the glass substrate and investigate the properties of thin film with adjusting the power of the target The result of materials analysis show amorphous structure and smooth surface And then we demonstrate MSM UV photodetectors It is found that the cutoff wavelength of the phototransistors can shift by changing the RF sputter power of the In2O3 target With 3 V applied bias it is found that measured cutoff wavelength are 315 nm 330 nm 340 nm respectively We have same results compared with the transmission spectrum analysis In the second part of the experiment the fabrication of thin film transistors and UV phototransistors are demonstrated by changing the power of targets In our experiment we totally realize nine different parameters of thin film transistors The optimized device sample E exhibits the great properties with a μFE of 8 45 cm2/Vs a SS of 0 43 V/decade and an on/off current ratio of 4 1×106 And then we apply a-MIO thin film to the thin film transistors it is found that the performance of the phototransistors are strongly dependent on the In2O3 The cutoff wavelength of the phototransistors is red-shift from 315 nm to 340 nm The photo-responsivity and DUV-to-visible rejection ratio of the fabricated are 0 39 A/W and 3 1×103 At last to further enhance the various electrical properties of thin film transistors so we use two ways to improve First because the cuprous oxide is p-type semiconductor then we deposit it on the thin film transistors to be the cap layer In this design it is found that thin film transistors is enhanced for electrical properties and stability and it exhibits μFE of 29 8 cm2/Vs a SS of 0 22 V/decade and an on/off current ratio of 1 2×106 Compared with the sample E it is found that we can achieve higher electrical properties Second the fabricated of a-MIO thin film transistors is inserted respectively two different buffer layer are demonstrated and the thin film transistors with Al2O3 buffer layer has better electrical properties The result can be contributed to the processing method of the buffer layer affects interface quality As mentioned above two improvement methods we know that it can enhance thin film transistors properties efficiently
Date of Award2016 Jul 5
Original languageEnglish
SupervisorShoou-Jinn Chang (Supervisor)

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