A novel method for preparing thin films with selective doping in a single evaporation step
A novel method for preparing thin films with selective doping in a single evaporation step
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一种在单一蒸发步骤中选择性掺杂制备薄膜的新方法
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发表时间：
1993
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通讯作者：
I. Rauf
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作者：
I. Rauf
表现出高光学透射率、热辐射的低发射率和良好导电性的薄膜具有重要的应用，例如用于电化学研究的透明电极、红外反射器、抗静电涂层、薄膜电阻器、抗静电涂层、各种太阳能电池上的降低电阻的顶层以及用于各种显示装置和成像管[1-5]。掺锡氧化铟（ITO）是此类材料中最好且研究最广泛的材料。所需的薄膜质量随着应用的复杂性而增加。实现最低可能的电阻率具有实际意义，因为它在膜厚度的选择上提供了一定的自由度，以实现高的光透射率，同时仍然保持低的薄层电阻。在保持高光学透明度的同时提高电阻率的努力包括：沉积后热处理[6]，阳离子和阴离子位点的掺杂[7]，以及多层氧化铟-氧化锡膜的生产[8]。可以降低电阻率并且尚未尝试的两种方法是：生长单晶氧化铟膜，然后外延生长Sn 2 O3薄膜，使得Sn 2 O3的单晶外延层提供自由电子，该自由电子然后可以在氧化铟层中移动的;以及用锡掺杂单晶氧化铟膜的顶部几层。这两种方法都需要非常昂贵的设备，并且对基底的选择施加了限制。因此，它们对于商业生产是不切实际的。除了实现尽可能低的电子迁移率外，本研究的其他主要目标是实现尽可能高的电子迁移率，并为长期争论的[9-12]锡掺杂氧化铟薄膜中的主要散射机制问题提供答案。本文报道了一种制备选择性掺杂薄膜的简单方法。其目的是设计一种简单的成本效益的方法来生产含有“区域”的膜，所述“区域”由重掺杂材料或相对高纯度的材料夹在所述“区域”之间。重掺杂的“区域”将充当自由电子发生器，而高纯度的“区域”将为电子提供路径。结果将是高的电子迁移率和电荷载流子密度，并且因此较低的电子迁移率。
Thin films exhibiting high optical transmission, low emissivity for thermal radiations and good electrical conductivity have important applications, such as transparent electrodes for electrochemical studies, infrared reflectors, antistatic coatings, thin-film resistors, antireflection coatings, resistance-reducing top layers on various solar cells and for a variety of display devices and imaging tubes [1-5]. Tin-doped indium oxide (ITO) is the best and most extensively studied material of this type. The required quality of the film increases with increasing sophistication of application. Achievement of the lowest possible resistivity is of practical significance, as it provides some freedom over the choice of film thickness to achieve high optical transmission while still maintaining low sheet resistance. Efforts to improve the resistivity while maintaining high optical transparency have included: postdeposition heat treatment [6], doping at both cation and anion sites [7], and production of multilayered indium oxide-tin oxide films [8]. Two methods which could reduce the resistivity and have not yet been tried are: growth of single-crystal indium oxide films followed by epitaxial growth of a thin film of Sn203, so that the single-crystal epilayer of S n 2 0 3 provides free electrons which could then be mobile in the indium oxide layers; and doping of the top few layers of a single-crystal indium oxide film with tin. Both of these methods require very expensive equipment and impose limitations on the choice of the substrate. Hence, they are impractical for commercial production. In addition to the achievement of the lowest possible resistivities, the other main objectives of the present research were to achieve the highest possible electron mobility and to provide an answer to the long-debated [9-12] question of the dominant scattering mechanism in tin-doped indium oxide films. This letter reports a very simple method for preparing selectively doped thin films. The objective was to devise a simple cost-effective method to produce films containing "zones" of heavily doped material sandwiches between the "zones" or relatively high-purity material. The heavily doped "zones" would act as free electron generators and the high-purity "zones" would provide a path for the electrons. The result would be high electron mobility and charge carrier density, and hence lower electri-