Mahmood, Ainorkhilah and Hassan, Zainuriah and Ahmed, Naser M and Yusof, Yushamdan and Yam, Fong Kwong and Chuah, Lee Siang
(2015)
High Sensitivity of Porous Si-Doped GaN MSM Photodetector using Thermally Untreated Platinum Contact.
In: 2nd Meeting of Malaysia Nitrides Research Group (MNRG 2015).
Abstract
this work. we report the formation of porous Si-doped GaN films under a novel alternating current
(sine-wave a.c. (50 Hz)) photo-assisted electrochemical (ACPEC) etching conditions. The ACPEC
formed porous GaN with excellent structural and surface morphology. Field emission scanning
electron microscope (FESEM), atomic force microscopy (AFM), photoluminescence (PL), Raman
spectra and high resolution X-ray diffraction (HR-XRD) phi-scan and rocking curves measurements
evidenced important features of the pore morphology, nanostructures and optical properties.
According to the FESEM micrographs, the GaN thin films exhibit a homogeneous nanoporous
structures with spatial nano-flakes arrangement. The AFM measurements revealed an increase in the
surface roughness induced by porosification. The porous layer exhibited a substantial PL intensity
enhancement with red-shifted band-edge PL peaks associated with the relaxation of compressive
stress. The shift of E2(high) to the lower frequency in Raman spectra of the porous GaN films further
confirms such a stress relaxation. X-ray diffraction phi-scan showed that porous GaN sample
maintained the epitaxial features. Thermally untreated platinum (Pt) finger contact was deposited on
the porous GaN to form MSM photodetector. The current-voltage (I-V) measurements indicated that
the devices were highly sensitive to ambient light. The photocurrent rise and decay times were
investigated under 365 nm chopped light and at bias voltages of 1, 3 and 5 V.
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