Positron measurements in Mg-doped GaN and development of digital Doppler broadening spectroscopy
Prozheeva, Vera (2012)
Tiivistelmä
In this work parameters of Mg-doped GaN samples were studied using positron
annihilation spectroscopy and analyzed. It is shown that gallium vacancies exist in
an unintentionally doped sample. Next, the sample with higher concentration of
Mg and low growth temperature contains vacancy clusters. In case of low
concentration of Mg the growth temperature does not affect the formation of
defects.
Analog electronics can be replaced by a modern digital device. While promising a
high quantity of benefits, the performance of these digitizers requires thorough
adjustment. A 14-bit two channel digitizer has been tested in order to achieve
better performance than the one of a traditional analog setup, and the adjustment
process is described. It has been shown that the digital device is unable to achieve
better energy resolution, but it is quite close to the corresponding attribute of the
available analog system, which had been used for measurements in Mg-doped
GaN.
annihilation spectroscopy and analyzed. It is shown that gallium vacancies exist in
an unintentionally doped sample. Next, the sample with higher concentration of
Mg and low growth temperature contains vacancy clusters. In case of low
concentration of Mg the growth temperature does not affect the formation of
defects.
Analog electronics can be replaced by a modern digital device. While promising a
high quantity of benefits, the performance of these digitizers requires thorough
adjustment. A 14-bit two channel digitizer has been tested in order to achieve
better performance than the one of a traditional analog setup, and the adjustment
process is described. It has been shown that the digital device is unable to achieve
better energy resolution, but it is quite close to the corresponding attribute of the
available analog system, which had been used for measurements in Mg-doped
GaN.