Applications of Epitaxial lift off technology for II-VI semiconductors

II-VI族半导体外延剥离技术的应用

基本信息

批准号：
EP/L025396/1
负责人：
Kevin Prior
金额：
$ 49.44万
依托单位：
Heriot-Watt University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2014
资助国家：
英国
起止时间：
2014 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FL025396%2F1
关键词：
Applications Epitaxial lift off technology

项目摘要

Semiconductor structures containing different materials are grown as thin film multilayers by techniques such as molecular beam epitaxy (MBE). MBE produces layers with excellent control of thickness but is limited to total thicknesses of just a few microns. In addition, growth takes place on a substrate, which is a highly crystalline template of a material such as gallium arsenide. After growth, the thin film layer remains bonded to the substrate.However, if one of the layers deposited is a so-called sacrificial layer soluble in a solvent (such as a weak acid) then all the layers deposited on top of it can be removed from the substrate. This process is called epitaxial lift off (ELO) and is advantageous in applications where the substrate is either not required or even hinders the operation of the device. Often using ELO means that the substrate can be recycled, which can reduce operating costs. An additional use for ELO is that the layers can be assembled into complex structures with many different types of materials. ELO layers can be transferred to intermediate flexible plastic substrates and patterned before assembly, so very complex structures can be produced.II-VI semiconductors are materials with a number of very useful properties, for example bandgaps ranging from 0 to 5eV. Other II-VI semiconductors have useful magnetic properties, for example some (e.g. CrS) are ferromagnets and others (e.g. MnS) are antiferromagnets. At Heriot-Watt University (HWU), we developed ELO for II-VI compounds using MgS sacrificial layers. The original method could only be used on small sample sizes (3mm square) but demonstrated many useful applications. Within the last few months we have developed a number of breakthroughs in II-VI ELO which show it has much more potential. In particular, we can remove pieces several square cm in size using a flexible plastic carrier. An additional very useful property is that when two ELO layers touch they will combine together, or stack, with the adhesion between layers so strong that they cannot be separated without breaking them.This proposal aims to develop this technology in 3 ways. First, we will show that ELO is easily extended to whole semiconductor wafers, and ELO layers can be transferred on flexible plastic carriers and patterned into small components. The components can be transferred again (stamped) to a final destination. All of this will be done with high (~100%) yield.Second, we will demonstrate the advantages of II-VI ELO by assembling 5 different demonstrator devices requested by our colleagues at HWU. We will supply these for evaluation as part of their own on-going research programmes. The devices include two types of sensors (temperature, and electric or magnetic fields), an optical diode, which only allows light propagation in one direction, a frequency doubler and a photonic bandgap structure. These structures are very difficult to produce by normal thin film growth techniques, but are easily produced by stacking ELO layers.The final strand of the programme develops the potential of ELO in different ways. The ability to move electrons or holes between ELO and adjacent layers would increase the number of applications: for example allowing us in future to develop photovoltaics or detectors. We will measure the electrical transport properties across ELO junctions between ZnSe and different materials and if possible modify them with different surface treatments.One surface treatment developed at HWU protects the II-VI layer surface after growth against contamination. At HWU it has worked for several months. We aim to show that it can be used to transport HWU ELO layers to City College, New York and show that it is possible to combine materials which are not available in the same MBE system and make ELO available to other groups.

包含不同材料的半导体结构通过分子束外延 (MBE) 等技术生长为薄膜多层。 MBE 生产的层具有出色的厚度控制能力，但总厚度仅限于几微米。此外，生长发生在基板上，该基板是砷化镓等材料的高度结晶模板。生长后，薄膜层仍然粘合到基板上。但是，如果沉积的其中一层是可溶于溶剂（例如弱酸）的所谓牺牲层，则沉积在其顶部的所有层都可以从基材上去除。该工艺称为外延剥离 (ELO)，在不需要衬底甚至妨碍器件运行的应用中具有优势。经常使用 ELO 意味着基材可以回收利用，从而可以降低运营成本。 ELO 的另一个用途是可以使用许多不同类型的材料将这些层组装成复杂的结构。 ELO 层可以转移到中间柔性塑料基板上，并在组装之前进行图案化，因此可以生产非常复杂的结构。II-VI 半导体是具有许多非常有用的特性的材料，例如带隙范围为 0 到 5eV。其他 II-VI 半导体具有有用的磁性，例如一些（例如 CrS）是铁磁体，另一些（例如 MnS）是反铁磁体。在赫瑞瓦特大学 (HWU)，我们使用 MgS 牺牲层开发了适用于 II-VI 化合物的 ELO。最初的方法只能用于小样本量（3 平方毫米），但展示了许多有用的应用。在过去的几个月里，我们在 II-VI ELO 中取得了许多突破，这表明它具有更大的潜力。特别是，我们可以使用柔性塑料载体去除几平方厘米大小的碎片。另一个非常有用的特性是，当两个 ELO 层接触时，它们会结合在一起或堆叠在一起，层之间的粘附力非常强，以至于在不破坏它们的情况下无法将它们分开。该提案旨在通过 3 种方式开发这项技术。首先，我们将展示 ELO 可以轻松扩展到整个半导体晶圆，并且 ELO 层可以转移到柔性塑料载体上并图案化为小型组件。组件可以再次转移（盖章）到最终目的地。所有这些都将以高（~100%）良率完成。其次，我们将通过组装 HWU 同事要求的 5 个不同的演示设备来展示 II-VI ELO 的优势。我们将提供这些用于评估，作为他们自己正在进行的研究计划的一部分。这些器件包括两种类型的传感器（温度、电场或磁场）、一个仅允许光沿一个方向传播的光学二极管、一个倍频器和一个光子带隙结构。这些结构很难通过普通的薄膜生长技术来生产，但通过堆叠 ELO 层很容易生产。该计划的最后一部分以不同的方式开发 ELO 的潜力。在 ELO 和相邻层之间移动电子或空穴的能力将增加应用的数量：例如允许我们将来开发光伏器件或探测器。我们将测量 ZnSe 和不同材料之间 ELO 结的电传输特性，并在可能的情况下使用不同的表面处理对其进行修改。HWU 开发的一种表面处理可保护生长后的 II-VI 层表面免受污染。在 HWU，它已经工作了几个月。我们的目标是展示它可以用于将 HWU ELO 层传输到纽约城市学院，并展示可以组合同一 MBE 系统中不可用的材料，并使 ELO 可供其他组使用。