Band‐Edge Photoluminescence at Room Temperature from ZnGeP 2 and AgGaSe 2

Photoluminescence near the band edge has been observed at room temperature from bulk single crystals of ZnGeP 2 and AgGaSe 2 . Both of these materials are ternary chalcopyrite semiconductors, but they have quite different edgerelated emission behavior. The emission from ZnGeP 2 is observed to peak near 2.35eV and is dominated by transitions from the upper Γ 7 conduction band to the upper Γ 6 valence band. The lack of emission at 1.99eV from the lowest Γ 6 conduction band in ZnGeP 2 indicates a Γ 6 conduction‐band‐energy minimum at the high‐symmetry point T (T 1 + T 2 band), rather than at Γ(k = 0). In contrast, AgGaSe 2 is a direct‐band‐gap semiconductor and exhibits k = 0 radiative recombination at 1.793 eV. Based on the power dependence of the PL emis‐ sion intensity, this 1.793 eV band is shown to be excitonic in nature, thus giving a room‐temperature band‐gap energy near 1.814 eV for AgGaSe 2 .