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Wurtzite-derived ternary I – III – O 2 semiconductors

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ABSTRACT

Ternary zincblende-derived I–III–VI2 chalcogenide and II–IV–V2 pnictide semiconductors have been widely studied and some have been put to practical use. In contrast to the extensive research on these semiconductors, previous studies into ternary I–III–O2 oxide semiconductors with a wurtzite-derived β-NaFeO2 structure are limited. Wurtzite-derived β-LiGaO2 and β-AgGaO2 form alloys with ZnO and the band gap of ZnO can be controlled to include the visible and ultraviolet regions. β-CuGaO2, which has a direct band gap of 1.47 eV, has been proposed for use as a light absorber in thin film solar cells. These ternary oxides may thus allow new applications for oxide semiconductors. However, information about wurtzite-derived ternary I–III–O2 semiconductors is still limited. In this paper we review previous studies on β-LiGaO2, β-AgGaO2 and β-CuGaO2 to determine guiding principles for the development of wurtzite-derived I–III–O2 semiconductors.

No MeSH data available.


Band gap variation as a function of x in the (1 − x)ZnO–x(LiGaO2)1/2 pseudo-binary system. The red dots and green dots indicate the band gaps determined for the ceramics and the films, respectively. The blue rectangle indicates a two phase region of Zn2LiGaO4 and β-LiGaO2 solid solutions. Although the boundary of the wurtzite-type phase and Zn2LiGaO4-type phase is between x = 0.1 and 0.2, all data are connected by one line, because both the phases are based on the wurtzite structure.
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Figure 3: Band gap variation as a function of x in the (1 − x)ZnO–x(LiGaO2)1/2 pseudo-binary system. The red dots and green dots indicate the band gaps determined for the ceramics and the films, respectively. The blue rectangle indicates a two phase region of Zn2LiGaO4 and β-LiGaO2 solid solutions. Although the boundary of the wurtzite-type phase and Zn2LiGaO4-type phase is between x = 0.1 and 0.2, all data are connected by one line, because both the phases are based on the wurtzite structure.

Mentions: The band gap of ZnO increases to 4.04 eV upon alloying with β-LiGaO2 as shown in Figure 3 [37, 38]. The largest band gap of the β-LiGaO2–ZnO alloy system is comparable with that of MgO–ZnO alloy films (∼4.0 eV) that are fabricated under non-equilibrium conditions [9, 10]. The band gap is significantly larger than that of MgO–ZnO alloys fabricated under equilibrium conditions (∼3.5 eV) [10, 11]. β-LiGaO2 enables a widening of the band gap of ZnO to ∼4 eV under equilibrium conditions because of its high solubility in ZnO, which arises from their structural similarity. Although the change in band gap depending on the alloying level exhibits bowing as observed in figure 3, the extent of the bowing is very small [38]. This also comes from the small lattice mismatch and the chemical mismatch, i.e., the band offset between β-LiGaO2 and ZnO.


Wurtzite-derived ternary I – III – O 2 semiconductors
Band gap variation as a function of x in the (1 − x)ZnO–x(LiGaO2)1/2 pseudo-binary system. The red dots and green dots indicate the band gaps determined for the ceramics and the films, respectively. The blue rectangle indicates a two phase region of Zn2LiGaO4 and β-LiGaO2 solid solutions. Although the boundary of the wurtzite-type phase and Zn2LiGaO4-type phase is between x = 0.1 and 0.2, all data are connected by one line, because both the phases are based on the wurtzite structure.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036475&req=5

Figure 3: Band gap variation as a function of x in the (1 − x)ZnO–x(LiGaO2)1/2 pseudo-binary system. The red dots and green dots indicate the band gaps determined for the ceramics and the films, respectively. The blue rectangle indicates a two phase region of Zn2LiGaO4 and β-LiGaO2 solid solutions. Although the boundary of the wurtzite-type phase and Zn2LiGaO4-type phase is between x = 0.1 and 0.2, all data are connected by one line, because both the phases are based on the wurtzite structure.
Mentions: The band gap of ZnO increases to 4.04 eV upon alloying with β-LiGaO2 as shown in Figure 3 [37, 38]. The largest band gap of the β-LiGaO2–ZnO alloy system is comparable with that of MgO–ZnO alloy films (∼4.0 eV) that are fabricated under non-equilibrium conditions [9, 10]. The band gap is significantly larger than that of MgO–ZnO alloys fabricated under equilibrium conditions (∼3.5 eV) [10, 11]. β-LiGaO2 enables a widening of the band gap of ZnO to ∼4 eV under equilibrium conditions because of its high solubility in ZnO, which arises from their structural similarity. Although the change in band gap depending on the alloying level exhibits bowing as observed in figure 3, the extent of the bowing is very small [38]. This also comes from the small lattice mismatch and the chemical mismatch, i.e., the band offset between β-LiGaO2 and ZnO.

View Article: PubMed Central - PubMed

ABSTRACT

Ternary zincblende-derived I–III–VI2 chalcogenide and II–IV–V2 pnictide semiconductors have been widely studied and some have been put to practical use. In contrast to the extensive research on these semiconductors, previous studies into ternary I–III–O2 oxide semiconductors with a wurtzite-derived β-NaFeO2 structure are limited. Wurtzite-derived β-LiGaO2 and β-AgGaO2 form alloys with ZnO and the band gap of ZnO can be controlled to include the visible and ultraviolet regions. β-CuGaO2, which has a direct band gap of 1.47 eV, has been proposed for use as a light absorber in thin film solar cells. These ternary oxides may thus allow new applications for oxide semiconductors. However, information about wurtzite-derived ternary I–III–O2 semiconductors is still limited. In this paper we review previous studies on β-LiGaO2, β-AgGaO2 and β-CuGaO2 to determine guiding principles for the development of wurtzite-derived I–III–O2 semiconductors.

No MeSH data available.