||In this thesis we reveal that the Ohmic contacts|
of n-type and p-type GaN are obtained by the
method of thermal evaporation. For different
types of GaN, different metals are used to
evaporate on GaN surface to form Ohmic contact.
The measurements of specific contact resistivity
were performed by TLM (transmission line model)
for different types of GaN. Also, we use a shadow
mask to form four Ohmic contacts on four corners
of GaN surface , and utilize the four contacts to
perform Hall measurement by Van der Pauw method.
By the data of Hall measurement, it indicates
that the specific contact resistivity of heavily
doped samples are smaller than lightly doped
samples. The effect of intensity photoluminescence
( PL ) spectrum of different annealing treatment
of p-type GaN are also demonstrated in this thesis.
And the carrier concentration of p-type GaN will
change with different annealing condition.
The method of C-V analysis is a powerful
technique to determine the parameters of device.
In this thesis, we exhibit completed formulation
of how to calculate all the parameters of MOS
structure, using Ga2O3/p-GaAs MOS structure as
calculated sample. The high frequency C-V curve
of Ta2O5/n-GaN MOS structure reveals a possibility
for fabricating a MOSFET using Ta2O5 as insulated
layer and GaN as substrate. In this thesis, we
utilize Ta2O5 as insulated material, because
Ta2O5 is a material with high dielectric constan.