Browsing by Author "Lai, WC"

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Electrical properties of multiple high-dose Si implantation in p-GaN
(1999-07-15)
Lai, WC
;
Yokoyama, M
;
Tsai, CC
;
Chang, CS
;
Guo, JD
This work performs Si ion implantation the electrical conductive type of the p-GaN film from p-type to n-type. Multiple implantation method is also used to form a uniform Si implanted region in the p-type GaN epitaxial layer. Implant energies for the multiple implantation are 40, 100, and 200 KeV. The implant dose is 5 x 10(15) cm(-2) for each implant energy. After implantation, the samples are annealed in a N-2 ambient for different annealing temperatures and annealing times. The activation efficiency reaches as high as 20% when annealing the sample at 1000 degrees C. The carrier activation energy is about 720 meV. The low activation energy indicates that the hopping process mechanism is the dominant mechanism for the activation of the Si implantation in p-GaN. Moreover, the rectifying I-V characteristic of the p-n GaN diode is also examined.
Electrical properties of the Si implantation in Mg doped p-GaN
(1999-11-01)
Lai, WC
;
Yokoyama, M
;
Tsai, CC
;
Chang, CS
;
Guo, JD
This work performs Si ion implantation to activate and convert the electrical conduction of p-GaN films from p-type to n-type. Multiple implantation method is used to form a uniform Si implanted region in the p-type GaN epitaxial layer. Implantation energies for the multiple implantation are 10, 100, and 200 keV. The implantation dose is 5 x 10(15) cm(2) for each implantation energy. After implantation, the samples were annealed in an N-2 ambient for different annealing temperatures and annealing times. The activation efficiency reaches as high as 20% when annealing the sample at 1000 degrees C,. The carrier activation energy is about 720 meV. The low activation energy indicates that the hopping process mechanism is the dominant mechanism for the activation of the Si implant in p-GaN. In addition, the rectifying I-V characteristic of the p-n GaN diode is also examined.
Epitaxial growth of the GaN film by remote-plasma metalorganic chemical vapor deposition
(1998-10-01)
Lai, WC
;
Chang, CY
;
Yokoyama, M
;
Guo, JD
;
Tsang, JS
GaN films were successfully grown by the remote-plasma metalorganic chemical vapor deposition (RPMOCVD) system. The composition of the GaN films could be tuned from nitrogen-rich to stoichiometric growth by varying the mole flow rate of trimethylgallium (TMGa). A hypothesis concerning the collisions between excited nitrogen and TMGa was also brought up. The collision between excited nitrogen and TMGa influences the characteristics of surface morphology, composition, growth rate, and growth mechanism. The characteristics of the GaN film were optimized by changing the growth conditions. The narrowest FWHM of the double-crystal X-ray rocking curve is about 0.2 degrees. Under optimized conditions, the composition of the GaN film is almost the same as that of the reference GaN film grown by MOCVD.