| Summary: | 碩士 === 國立交通大學 === 電子物理系 === 87 === LEC(Liquid Encapsulated Czochralski) and semi-insulating GaAs(100) wafers are implanted at the
room temperature with 160 keV N+ to a fluence of cm-2. Rapid thermal annealing is performed at
950℃ for 30 seconds while furnace annealing is used below 700℃ for 30 minutes. After annealing
at as high as 950℃, N shows no measurable redistribution by secondary ion mass spectrometry.
From X-ray diffraction, it is found that the annealing temperature up to 500℃ is necessary for the
crystalline regrowth.
Electrical characteristics of the material are investigated in details. From temperature-dependent
conductance measurement, the carrier transport for as-implanted sample is identified to be
variable-range hopping. The samples annealed above 500℃ become highly resistive. By current-voltage,
admittance spectroscopy, and deep level transient spectroscopy measurements, it is found that the
high-resistive material shows the characteristic of a space-charge-limited current conduction governed by
traps. The activation energy of the material resistance is found to increase with increasing annealing
temperature. Admittance spectroscopy displays that the activation energy of material resistance for
as-implanted sample is 0.20eV which increases to 0.34, 0.59, and to 0.71eV after annealing at 500℃,
700℃, and 950℃, respectively.
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