Anomalous temperature dependence of the band gap in AgGaSe2 and AgInSe2

Optical properties of single-crystalline chalcopyrite semiconductor AgInSe2

“…Polarization-dependent photoconductivity and wavelength-derived reflectivity were measured by Tell et al 22 in the fundamental absorption edge of single-crystalline AgInSe 2 samples. Aliyev et al 23 also measured photoconductivity spectra of single-crystalline AgInSe 2 at T = 77-300 K, but paid no attention to light polarization.…”

“…1 Silver indium diselenide ͑AgInSe 2 ͒ is one of the I-III-VI 2 ternary compounds, but its many fundamental properties are not sufficiently evaluated or even unknown. 1,2 The optical properties of AgInSe 2 have been studied using various techniques, such as far-infrared ͑IR͒ reflectivity, 3 optical absorption, 4-14 near-IR-ultraviolet reflectivity, 7,9,15 photoluminescence ͑PL͒, 10,16-21 photoconductivity, [22][23][24][25] spectroscopic ellipsometry ͑SE͒, 26,27 electroreflectance ͑ER͒, 16 thermoreflectance ͑TR͒, 27 and wavelength-derivative reflectivity. 22 Most of these studies were carried out on polycrystalline AgInSe 2 samples.…”

Optical absorption and photoreflectance spectroscopy of the single-crystalline chalcopyrite semiconductor AgGaSe2

“…Although the material has been the subject of many research efforts, many fundamental properties are not sufficiently evaluated or are even unknown. 9 The optical properties of AgGaSe 2 have been studied using various techniques, such as far-infrared (IR) reflectivity, 10 near-IR-ultraviolet reflectivity, [11][12][13][14][15] optical absorption, [16][17][18][19][20][21][22][23][24][25][26] photoluminescence (PL), 11,19,[27][28][29][30][31][32][33] photoconductivity, [34][35][36][37] cathodoluminescence, 38 spectroscopic ellipsometry (SE), 39 electroreflectance (ER), 16 and photoreflectance (PR). 21 Most of these studies were carried out on polycrystalline AgGaSe 2 samples.…”

“…21 Most of these studies were carried out on polycrystalline AgGaSe 2 samples. 14,[21][22][23]25,26,[28][29][30]32,34,35 Miller et al 10 grew singlecrystalline AgGaSe 2 and measured far-IR reflectivity using polarized light. PL measurements on single-crystalline AgGaSe 2 samples were performed by several authors; 28,31,33 however, polarization dependence was not taken into consideration.…”

“…12,15,21,26,31,34 Artus and Bertrand 15 performed reflectivity measurement on singlecrystalline AgGaSe 2 from 5 to 295 K. They observed the positive temperature-coefficient value of dE g /dT below 70 K, but they gave no detailed analysis on E g (T) data. Aliyev et al 34 measured the photoconductivity spectra on a chemical-transport-grown AgGaSe 2 crystal from 77 to 300 K, and obtained the positive temperature-coefficient value of dE g /dT below 120 K. This result was, however, deduced from only the limited E g (T) data. Recently, Ozaki et al 21 and Calder on et al 26 measured optical absorption spectra on Bridgmangrown AgGaSe 2 crystals, and obtained E g (T) data.…”