Turkish Journal of Physics
Abstract
Absorption measurements were carried out in GaSe and GaSe:Gd samples in temperature range 10-320 K in steps 10 K. The first and the second (n=1 and n=2) excitonic levels were marked. The first exciton energies for n=1 were calculated as 2.118, 2.008 eV in GaSe, and 2.125, 2.006 eV in GaSe:Gd at 10, 320 K and respectively. The second exciton energies for n=2 were calculated as 2.140, 2.125 eV in GaSe at 10, 80 K and 2.141, 2.120 eV in GaSe:Gd at 10, 120 K and respectively. Binding energies of GaSe and GaSe:Gd were calculated as (29.46\pm 1 and 21.33\pm 1 meV), respectively. The direct band gaps were estimated as 2.147, 2.037 eV in GaSe and 2.146, 2.027 eV in GaSe:Gd at 10, 320 K and respectively. There are abrupt changes in the Urbach energy for GaSe at 100 and 240 K, and GaSe:Gd at 90 and 220 K. However, there are abrupt change both in the steepness parameter for GaSe:Gd at 90, 240 K and in the \sigma _{0} values for GaSe:Gd at 70 and 240 K. These temperatures obtained from the changing of the steepness parameter, \sigma _{0} values and Urbach energy may be at phase transition temperatures.
DOI
-
Keywords
GaSe, GaSe:Gd, exciton, Urbach tails, binding energy, phase transition.
First Page
315
Last Page
325
Recommended Citation
GÜRBULAK, BEKİR (2001) "Exciton Investigations and the Urbach Tails of Gd Doped and Undoped GaSe," Turkish Journal of Physics: Vol. 25: No. 4, Article 4. Available at: https://journals.tubitak.gov.tr/physics/vol25/iss4/4
