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New forms of silicon with enhanced optoelectronic properties

具有增强光电特性的新型硅

基本信息

批准号：
1809756
负责人：
Timothy Strobel
金额：
$ 29.59万
依托单位：
Carnegie Institution of Washington
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-07-01 至 2023-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1809756&HistoricalAwards=false
关键词：
New forms silicon enhanced optoelectronic

项目摘要

Nontechnical description: Unlike metals that freely conduct electricity, semiconductors require energy input to promote electrons into conducting states. The minimum input energy, known as the band gap, is either direct or indirect depending on the specific crystalline structure. Silicon, which is essential for the vast majority of modern electronics and solar energy devices, possesses an indirect band gap meaning that light absorption and emission are feeble processes. In contrast, direct band gap materials are effective absorbers and emitters of light. Recent theoretical calculations indicate energetic feasibility for numerous forms of crystalline silicon with direct band gaps, but experimental synthesis pathways are not available. This research team aims to create entirely new forms of crystalline silicon that possess direct band gaps in order to improve optoelectronic properties that impact a range of technologies including solid-state detectors, optical communication and energy conversion devices. Research is focused on novel synthetic pathways that combine high- and low-pressure experiments in order to achieve access to kinetically-stabilized states. More generally, the development of novel synthesis methodologies broadly affects metastable materials beyond silicon. This research project occurs within an educational environment that emphasizes the career development of students and postdoctoral scholars. Technical description: This project utilizes a new approach for metastable materials synthesis through a combined high-pressure / ambient-pressure hybrid method. Numerous metastable silicon allotropes with enhanced optoelectronic properties are predicted to exist within 30 kJ/mol of the ground state, but effective synthesis pathways are lacking. By initiating ambient-pressure chemical synthesis from precursors formed under high-pressure conditions, entirely new synthesis pathways are possible due to the high-energy state of the recovered precursor that is metastable at ambient conditions. This effort explores the depth of realizable materials in silicon and probes the relationships between metastable allotropes and optoelectronic properties in order to create entirely new metastable crystalline allotropes that possess direct or quasidirect band gaps. The research contributes to the longstanding limitations associated with the indirect band gap of the cubic diamond structure. Experiments are conducted at high-pressure conditions in order to optimize single-crystalline growth and at low-pressure conditions to optimize precursor transformations. The intrinsic optical and electronic transport properties of novel silicon allotropes are established experimentally, and the library of potential high-pressure precursor materials is supported by calculations including density functional theory-based structure searching. The overall goal of the project is to produce and characterize new silicon phases exhibiting improved optical activity.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术性描述：与自由导电的金属不同，半导体需要能量输入来促进电子进入导电状态。最小输入能量，称为带隙，取决于具体的晶体结构，是直接的或间接的。硅对于绝大多数现代电子和太阳能设备至关重要，它具有间接带隙，这意味着光吸收和发射是微弱的过程。相反，直接带隙材料是光的有效吸收体和发射体。最近的理论计算表明，具有直接带隙的多种形式的晶体硅的能量可行性，但实验合成途径不可用。该研究团队旨在创造具有直接带隙的全新形式的晶体硅，以改善影响一系列技术的光电特性，包括固态探测器，光通信和能量转换设备。研究的重点是新的合成途径，结合联合收割机高压和低压实验，以实现获得动力学稳定的状态。更一般地说，新的合成方法的发展广泛地影响了硅以外的亚稳材料。该研究项目发生在强调学生和博士后学者职业发展的教育环境中。技术说明：该项目采用了一种新的方法，通过高压/常压混合方法合成亚稳材料。许多具有增强的光电性能的亚稳硅同素异形体被预测存在于基态的30 kJ/mol内，但缺乏有效的合成途径。通过从在高压条件下形成的前体开始环境压力化学合成，由于回收的前体在环境条件下是亚稳态的高能状态，全新的合成途径是可能的。这项工作探索了硅中可实现材料的深度，并探索了亚稳同素异形体与光电性能之间的关系，以创造具有直接或准直接带隙的全新亚稳晶体同素异形体。这项研究有助于与立方金刚石结构的间接带隙相关的长期限制。实验在高压条件下进行，以优化单晶生长，并在低压条件下进行，以优化前体转化。实验建立了新型硅同素异形体的固有光学和电子输运性质，并通过包括基于密度泛函理论的结构搜索的计算来支持潜在的高压前体材料库。该项目的总体目标是生产和表征具有更高光学活性的新硅相。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

期刊论文数量（5）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Bulk Crystalline 4H -Silicon through a Metastable Allotropic Transition

块状晶体 4H - 亚稳态同素异形转变硅

DOI：
10.1103/physrevlett.126.215701
发表时间：
2021
期刊：
Physical Review Letters
影响因子：
8.6
作者：
Shiell, Thomas B.;Zhu, Li;Cook, Brenton A.;Bradby, Jodie E.;McCulloch, Dougal G.;Strobel, Timothy A.
通讯作者：
Strobel, Timothy A.

Origin of pressure-induced band gap tuning in tin halide perovskites