S-Space College of Engineering/Engineering Practice School (공과대학/대학원) Dept. of Electrical and Computer Engineering (전기·정보공학부) Theses and dissertations (학위논문_전기·정보공학부)
Field emission display controlled by metal-oxide-semiconductor field effect transistor
MOSFET 으로 제어되는 전계 방출 디스플레이
- Issue Date
- 서울대학교 대학원
- FEA; FEA; MOSFET; MOSFET; MCFEA; MCFEA; 균일도; uniformity; MCFED; MCFED; 단일 칩FED; one-chip FED
- Thesis(doctors)--서울대학교 대학원 :전기공학부,2008.2.
- The concept for MOSFET controlled FEA is introduced as a method to improve a uniformity and a stability of field emission current. MCFEA is the device in which the field emission current is controlled by MOSFET. The structure of the MOSFET is a serial connection of a high threshold voltage and a low threshold voltage MOS structures. The structure of MOSFET for an MCFEA is designed to sustain the drain voltage over 80 V. The simulation results showed that the drain current was nearly independent of the low threshold voltage region length. The low voltage driver circuit operated under 10 V can be used because the MOSFET controls the emission current of several ?A, which is the typical current level needed in a pixel of FED, in the voltage range of 10 V. The fabrication process of MCFEA is based on the current semiconductor process technology using silicon substrate. The device showed the improved current drivability and emission stability compared with the conventional FEA. An MCFED was fabricated and characterized. The fabricated FEAs, HV-MOSFETs and MCFEAs worked well as desired. HV-MOSFET was proven to endure high drain voltage over 80 V which is the operation voltage of FEA. The I-V characteristics of MCFEA showed that the emission currents of FEA were well controlled according to the control gate voltage of high voltage MOSFET. Therefore, the MCFEA has the sufficient characteristics to be used as the cathode of MCFED. The evaluation of MCFED was carried out in a high vacuum chamber to escape the problem resulted from packaging. The emission images of the MCFED showed the precise operation. From the comparison with a conventional FED, MCFED showed better performance. Uniformity indices of a conventional FED and MCFED were 28.9 % and 92.6 %, respectively. To integrate the driver circuit with MCFEAs, one-chip FED process is developed in which high voltage MOSFET, low voltage MOSFET and FEA should be integrated on the same substrate. Field implantation steps for HV-MOSFET and LV-MOSFET were separated to meet the condition of breakdown voltage and field threshold voltage. Sidewall spacer technique was used to increase breakdown voltage of LV-MOSFET for driver circuit and to make the step of polysilicon gate smooth for overlapped metal line. The discrete devices of one-chip FED, HV-MOSFET, LV-MOSFET and MCFEA , operated well as designed.
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