A certain photovoltaic material has a minimum band-gap energy of 1.10 eV
PHYSICS · Multi-part · CBSE · Physics · Dual Nature of Radiation and Matter · Dual Nature of Radiation and Matter
Problem
A certain photovoltaic material has a minimum band-gap energy of 1.10 eV. Only photons whose energy equals or exceeds this value can excite an electron from the valence band to the conduction band.
Assume all needed physical constants are available on the exam information sheet.
(a) Determine the longest wavelength photon that can excite an electron across the band gap in this material. Show your work and include units.
(b) Identify the region of the electromagnetic spectrum (infrared, visible, ultraviolet, etc.) in which this wavelength lies, and briefly justify your classification.
(c) During an experiment the material is illuminated with a pulse containing 1.0 µJ of photons, each having the wavelength found in part (a). Estimate the number of photons in the pulse.
(d) Explain why photons whose wavelength is 1.5 times longer than the value found in part (a) are unable to produce electron–hole pairs in this material.