We investigated graphene-based transparent electrodes for InGaN/GaN light emitting diodes(LED). Nano-dotted layer of Ag and Ni were inserted between p-GaN and graphene to achieve low contact resistance and high transmittance. Heat treated Ag layer/graphene had low contact resistance of 0.7~1.2Ω/cm2, and we could achieve better luminance for GaN-based LED. However, for patterned Ni layer/graphene
band of the two semiconductors determines a charge transfer,
creating a triangular potential.
3. Polarization
- AlGaN/GaN HEMTs transistor don’t need doping to obtain a high electron density.
4. Contacts
- Source / Drain : Ohmic contact, Carrier could move free Metal ↔ Semiconductor.
- Gate : Schottky contact, controlled transistor to turn on / off.
5. Summary
어떻게?
① Metal을 이용
☞ Contact Resistance ↓, but Transmittance ↓
② Graphene을 이용
☞ Transmittance ↑, but Contact Resistance ↑
③ Metal/Graphene layer를 이용
☞ Transmittance ↑, Contact Resistance ↓
④ Patterned metal + Graphene을 이용 !! ↕:Good
☞ Transmittance ↑↑, Contact Resistance ↓↓ ↕: Bad
V-led는 아래에서부터 순서대로 metal substrate(p-type electrode의 역할을 함), reflector, P-GaN, MQW, N-GaN, n-electrode의 구조 순서로 쌓여있는 것을 확인할 수 있다.
기존의 LED와는 다르게 metal substrate를 지지대로 붙어 있기 때문에 p-type electrode가 n-type보다 아래쪽으로 오도록 배열시킨 특이한 구조이다. 또한 아랫부