Transcript 下載/瀏覽Download

S.H CHEN
1
Outline
•
•
•
•
•
Introduction
Experiment
Results and discussion
Conclusion
References
2
Introduction
• Placing the DBR below the active layer prevents from optical
power losses due to absorption in the substrate and, directing
the light into the active area of the structure.
• The most common methods used to implement the DBR
structures under the active GaN thin film area are: (1)
Epitaxially grown monolithic (Al, Ga, In)N/GaN periodic
stacks (2)External bonded dielectric mirrors and (3)Etched airgap structures.
3
Experiment
50nm
4
n-type Doping ~1018 cm3
3.5對SL
5
Results and discussion
雷射光源(514nm)
小圖雷射光源(325nm)
520nm
6
265nm 365nm 480nm
7
360nm
8
9
Conclusion
• However, although our approach demonstrates sufficient
optical quality for MSM UV photo-detector test structure
action, it still presents clear limitations: It must be stated that
the here discussed UV MSM GaN on Si approach with
embedded Y2O3/Si based DBR by MBE is still on the level of
a physics “proof of principle” study and cannot compete with
advanced III-N
10
Conclusion(2)
• Further improvement of the MSM UV photo-detector
performance is currently in progress by (a)improving the GaN
thin film structure quality by reducing defect densities and
intrinsic charge carrier concentrations and (b) decreasing the
dark current of the Schottky contact by adding a leakage
current suppressing oxide layer between Ir metal contacts and
GaN surface
11
References
• Enhanced ultraviolet GaN photo-detector response on Si(111)
via engineered oxide buffers with embedded Y2O3/Si
distributed Bragg reflectors
12
Thank you for your attention
13