반도체실험 Metal contacts and diodes

소개

"반도체실험 Metal contacts and diodes"에 대한 내용입니다.

목차

Ⅰ. Schottky Barrier Diode
1. Explain three ways to control the thickness of the spin-coated photoresist.
2. Explain several photolithography techniques including positive, negative, and image reversal lithography.
3. Explain the principle of Schottky barrier diode and p-n junction diode and compare them.
4. I-V Analysis
5. Explain the reason why the four point probe measurement is used for measuring specific contact resistance with Transmission Line Method (TLM).

Ⅱ. Light-Emitting Diode
6. Compare PL and EL from the LED wafer and explain if there is a difference in the peak emission wavelength (Use 20mA data for EL).
7. In the EL, compare EL intensity as a function of injection current, check if there is linear increase in intensity or not, and explain.
8. Estimate the bandgap energy from the LED IV curve. Is there any difference compare to the PL or EL peak wavelength? Explain.

Reference

본문내용

1. Explain three ways to control the thickness of the spin-coated photoresist.
Spin coating은 photoresist(PR)를 film과 같이 uniform하게 만드는 방법이다. PR을 substrate에 떨어뜨리고 수천 RPM으로 회전시킴으로써 PR을 spread 시킨다. 최종 thickness는 물질의 viscosity, surface tension, 그리고 final rotational speed, acceleration 등에 따라 달라진다. 그중 세가지에 대해 알아보자.
첫번째는 spin coating에 있어서 가장 중요한 요소인 spin speed다. RPM은 centrifugal force, velocity는 물론, 바로 위 공기의 characteristic turbulence에 기여한다. Spin speed가 빠를수록 thickness는 감소하며 일반적으로 angular speed의 제곱근에 반비례한다고 알려져 있다.
두번째는 spin time이다. Spin time이 짧을수록 thickness가 두꺼우며 spin time이 길수록 thickness가 얇다. 이는 wafer가 final speed로 acceleration 되는 데에 충분한 시간이 필요하기 때문이다. 균일하게 만드는 과정 또한 어느 정도의 시간이 요구되며, PR의 dry도 spin time에 의존한다. 일반적으로 resist가 viscous할수록, spin speed가 느릴수록 time window가 증가한다.
마지막은 temperature와 humidity다. PR 내 solvent의 evaporation rate는 substrate 주위의 air surrounding에 의존한다. Humidity가 낮을수록, temperature가 높을수록 evaporation rate가 증가한다. 더욱이, 높은 온도에서는 viscosity가 감소한다. 따라서 이들도 thickness를 결정한다고 할 수 있다.

참고자료

· MicroChemicals, Basics of Microstructuring, Spin-coating
· University of Louisville (2013), “Spin coating theory”, Micro/Nano Technology Center
· M.D. Tyona (2013), “A theoretical study on spin coating technique”, Advances in Materials Research, 2(4), 195-208
· Ben G. Streetman and Sanjay Kumar Benergee, Solid state Electronic Devices 7th, PEARSON(2016)
· Yuan Taur and Tak H. Ning, Fundamentals of Modern VLSI Devices, CAMBRIDGE(2009)
· Wikipedia, Stark shift
· Prof. Jong Kyu Kim, Course Outline/Lab Manual : Metal contacts and diodes(2019)
· Wojciech MACHERZYNSKI et al. (2016), “Formation Process and Properties of Ohmic Contacts Containing Molybdenum to AlGaN/GaN Heterostructures”, Applied Physics, 14(1)
· Lisa M. Porter and Robert F. Davis (1995), “A critical review of ohmic and rectifying contacts for silicon carbide”, Materials Scicence and Engineeing, B34, 83-105
· Zhongchang Wang et al. (2009), “Ohmic contacts on silicon carbide: The first monolayer and its electronic effect”, Physical Review, B 80, 245303
· Horng-Shyang Chen et al. (2014), “Independent variations of applied voltage and injection current for controlling the quantum confined Stark effect in an InGaN/GaN quantum-well light-emitting diode”, Optics Express, 22(7)
· Takashi MUKAI, Kazunori TAKEKAWA and Shuji NAKAMURA (1998), “InGaN-Based Blue Light-Emitting Diodes Grown on Epitaxially Laterally Overgrown GaN Substrates” Jpn. J. Appl. Phys. 37, 839-841
· Yun Ji et al. (2014), “Comparative study of field-dependent carrier dynamics and emission kinetics of InGaN/GaN light-emitting diodes grown on (11 2 -2) semipolar versus (0001) polar Planes” Applied Physics Letters 104, 143506
· A. Hori, D. Yasunaga, A. Satake, and K. Fujiwara (2003), “Temperature and injection current dependence of electroluminescence intensity in green and blue InGaN single-quantum-well light-emitting diodes”, Journal of Applied Physics, 93(6), 3152-3157