Pressure-Induced Transition from Wurtzite and Epitaxial Stabilization for Thin Films of Rocksalt MgSnN2
Pressure-Induced Transition from Wurtzite and Epitaxial Stabilization for Thin Films of Rocksalt MgSnN2
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DOI：
10.1021/acs.chemmater.2c03671
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发表时间：
2023-03
影响因子：
8.6
通讯作者：
Kaede Makiuchi;F. Kawamura;J. Jia;Yelim Song;Shunichiro Yata;H. Tampo;H. Murata;N. Yamada
中科院分区：
文献类型：
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作者：
Kaede Makiuchi;F. Kawamura;J. Jia;Yelim Song;Shunichiro Yata;H. Tampo;H. Murata;N. Yamada
无机化合物中高压相的薄膜合成仍然是一个挑战。以薄膜形式合成高压相为创造独特的光电器件提供了潜在的机会，因为高压相通常表现出在环境相中无法获得的有趣特性。我们研究了近年来才发现的具有岩盐结构（rs-MTN）的MgSnN 2的高压相。rs-MTN是一种直接带隙化合物，其（111）面与GaN（001）面完全匹配，这意味着rs-MTN是一种很有前途的光电材料，可用于发光二极管和叠层太阳能电池。然而，单相rs-MTN从未以薄膜或单晶形式合成。在此，单相rs-MTN薄膜成功地通过两条路线合成。一种是纤锌矿型MTN前体层的高压热处理，另一种是使用反应共溅射在等结构MgO（111）衬底上直接生长。前一条路线利用了压力诱导的纤锌矿到岩盐的转变，并且是基于第一性原理计算设计的，该计算预测转变压力为108 GPa。后一种途径利用MgO的（111）平面上的外延稳定。直接生长的rs-MTN薄膜具有光滑的表面，使其光电性能的调查。结果表明，rs-MTN薄膜为n型半导体，电子密度为1017 cm-3量级，禁带宽度为2.3eV。这些发现为开发rs-MTN作为光电半导体提供了平台。
The thin-film synthesis of high-pressure phases in inorganic compounds remains a challenge. The synthesis of high-pressure phases in thin-film form opens potential opportunities for creating unique optoelectronic devices because high-pressure phases often exhibit intriguing characteristics that cannot be accessed in ambient phases. We investigated a high-pressure phase of MgSnN2with the rocksalt structure (rs-MTN) which has only been identified in recent years. rs-MTN is a direct-gap compound, and its (111) plane matches perfectly with GaN(001), which implies that rs-MTN is a promising candidate for optoelectronic materials for light-emitting diodes and tandem solar cells. However, single-phase rs-MTN has never been synthesized in either thin-film or single-crystalline forms. Herein, single-phase rs-MTN thin films were successfully synthesized via two routes. One was the high-pressure heat treatment of wurtzite-type MTN precursor layers, and the other was direct growth onto isostructural MgO(111) substrates using reactive co-sputtering. The former route exploited the pressure-induced wurtzite-to-rocksalt transition and was designed based on first-principles calculations that predicted a transition pressure of ∼8 GPa. The latter route utilized epitaxial stabilization on the (111) plane of MgO. The direct growth of the rs-MTN films with smooth surfaces enabled the investigation into their optoelectronic properties. Consequently, the rs-MTN films were found to be n-type semiconductors with electron densities of an order of 1017cm–3and a band gap of 2.3 eV. These findings provide a platform for developing rs-MTN as an optoelectronic semiconductor.