  Violet phosphorus (VP) has garnered attention for its appealing physical
properties and potential applications in optoelectronics. We present a
comprehensive investigation of the photo-degradation and thermal effects of
exfoliated VP on SiO2 substrate. The degradation rate of VP was found to be
strongly influenced by the excitation wavelength and light exposure duration.
Light exposure to the above bandgap ({\lambda} > 532 nm) leads to faster
degradation, attributed to interactions with reactive oxygen species.
Power-dependent photoluminescence (PL) measurements at low temperature (T=4 K)
showed neutral exciton (X0) and trion (T) intensities linearly increased with
excitation power, while the energy difference between their peak energies
decreased, indicating changes in the exciton energy gap due to degradation. At
room temperature X0 and T peaks were observed with higher X0 spectral weight,
indicating reduced thermal stability of T. As the temperature decreased to 4 K,
both X0 and T emissions intensified with blue-shifted peak positions. The T/X0
spectral weight ratio increased from 0.28 at 300 K to 0.69 at 4 K, suggesting
enhanced T formation due to reduced phonon scattering. Temperature-dependent
Raman spectroscopy revealed the presence of VP up to 673K. By tracking the peak
position of 9 Raman modes with temperature the linear first-order temperature
coefficient were obtained and found to be linear for all modes up to 673 K. Our
results provide a deeper understanding of VP's degradation behavior and
implications for optoelectronic applications.
