期刊
ACS APPLIED ENERGY MATERIALS
卷 5, 期 6, 页码 6847-6854出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsaem.2c00485
关键词
thermoelectricity; defect engineering; III-nitride semiconductors; scandium nitride; ion irradiation; irradiation-induced defects; molecular beam epitaxy
资金
- International Center for Materials Science (ICMS)
- Sheikh Saqr Laboratory (SSL) in JNCASR
- Science and Engineering Research Board (SERB) of the Government of India [SRG/2019/000613, CRG/2020/006190]
Researchers introduced native defects into ScN thin films through lithium ion irradiation and found that these defects positively impact ScN's thermoelectric properties by increasing its Seebeck coefficient and reducing its thermal conductivity.
Scandium nitride (ScN) is an emerging rocksalt indirect bandgap semiconductor with the potential to overcome some of the limitations of traditional wurtzite III (A)-nitride semiconductors in next-generation optoelectronic and thermoelectric applications. Epitaxial ScN thin films contain point defects such as oxygen impurities that result in a high carrier concentration and help achieve a high thermoelectric power factor. However, due to its high thermal conductivity, the thermoelectric figure-of-merit (zT) of ScN is relatively low. Recent theoretical calculations have suggested that scandium and nitrogen vacancies in ScN introduce asymmetric states close to the Fermi energy, increasing its Seebeck coefficient. Increased phonon scattering by these native defects should also reduce thermal conductivity to help achieve higher zT. However, incorporating such native defects in as-deposited ScN is challenging due to their high formation energies. In this work, we introduce native defects in molecular beam epitaxy (MBE)-deposited ScN thin films by lithium-ion irradiation and study the impact of such native defects on ScN's thermoelectric properties. Consistent with theoretical calculations, we find that the Seebeck coefficient in irradiated ScN thin films increases significantly. Thermal conductivity decreases by more than half to 7 +/- 1 W/(m.K) at room temperature due to phonon scattering by the irradiation-induced defects. Despite a reduced electrical conductivity due to scattering from defects, irradiated ScN thin films exhibit a high power factor similar to(1-2) x 10(-3) W/(m.K-2) in the 300-950 K range and show a modest increase in the overall zT. This work highlights the multifunctionality of irradiation-induced defects in engineering thermoelectric properties of transition metal nitride semiconductors.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据