page_title: I-III-VI semiconductors
section_title: AgGaO2 and AgAlO2
hierarchical_section_title: I-III-VI semiconductors / AgGaO2 and AgAlO2
caption_attribution_description: Variation of optical band gap of the (1 − x)ZnO–x(AgGaO2)1/2 alloys (red dots and line) as a function of the alloying level, x, together with that reported for the (1 − x)–xCdO alloys (green dots and line) for comparison.
context_page_description: I-III-VI₂ semiconductors are solid semiconducting materials that contain three or more chemical elements belonging to groups I, III and VI of the periodic table. They usually involve two metals and one chalcogen. Some of these materials have a direct bandgap, Eg, of approximately 1.5 eV, which makes them efficient absorbers of sunlight and thus potential solar cell materials. A fourth element is often added to a I-III-VI₂ material to tune the bandgap for maximum solar cell efficiency. A representative example is copper indium gallium selenide
context_section_description: Similarly to CuGaO₂, α-AgGaO₂ and α-AgAlO₂ have the delafossite crystal structure while the structure of the corresponding β phases is similar to wurtzite (space group Pna2a). β-AgGaO₂ is metastable and can be synthesized by ion exchange with a β-NaGaO₂ precursor. The bandgaps of β-AgGaO₂ and β-AgAlO₂ (2.2 and 2.8 eV respectively) are indirect; they fall into the visible range and can be tuned by alloying with ZnO. For this reason, both materials are hardly suitable for solar cells, but have potential applications in photocatalysis.
  Contrary to LiGaO₂, AgGaO₂ can not be alloyed with ZnO by heating their mixture because of the Ag⁺ reduction to metallic silver; therefore, magnetron sputtering of AgGaO₂ and ZnO targets is used instead.
caption: Bandgap in AgGaO2-ZnO and CdO-ZnO alloys.[2]
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