Al induced crystallization of a-Si

Abstract

The crystallization of amorphous Si induced by Al during heat treatment has been investigated by cross section and plan view transmission electron microscopy. The lowest temperature of Al induced crystallization of amorphous Si was found to be 440 K. The crystallization temperature, however, depends on the thickness of Al layers in layered structures and on the concentration of Al in co-deposited layers below 1-nm-layer thickness and 15 at.% of Al concentration, respectively. Al-induced crystallization in layered structures starts at the Al/amorphous Si interfaces and is located close to them. The amount of crystallized Si depends on the quantity of Al and on the temperature and increases with them. The mechanism of crystallization involves intermixing of Al with Si and the formation of an alloy of high metal concentration in the amorphous/crystalline interface. When the formation of this alloy is not assured due to low Al concentration, then crystallization does not start or the process of crystallization stops. In Al induced crystallization the nucleation of polycrystalline Si grains rather than their crystal growth is affected.

The Role of Au in the Thermoelectric Properties of Amorphous Ge/Au and Si/Au Thin Films

“…9 It has been reported that, in codeposited films of SiAl, which are a uniformly mixed state of amorphous Si and metal, the formation of metallic or metal-rich clusters is necessary before crystallization of amorphous Si. 10 The same effect could be considered as taking place with Si/Au or Ge/Au thin films. In this study, the intended value of the Au layer thickness of the thin films was 0.2 nm to 0.4 nm.…”

“…Contact with a metal can drastically reduce the temperature at which amorphous Si or amorphous Ge crystallizes. [9][10][11][12] Figure 2a, b also shows XRD profiles of Ge/Au (0/4.8/0.2) and (0/4.6/0.4) thin films, as-deposited and annealed at various temperature. Both as-deposited samples (0/4.8/0.2) and (0/4.6/0.4) had broad amorphous phase profiles.…”

Low temperature polycrystalline silicon film formation by metal induced crystallization with nickel salt derived by ultrasonic spray pyrolysis

“…As a promising lowtemperature crystallization approach, metal induced crystallization (MIC) has been extensively studied. A layer of metal, for example, Al [1], Au [2], Ni [3], is deposited on top of a-Si and used as mediating layer to initiate the crystallization by forming nucleation centers in the low-temperature annealing process [4].…”

Employing the effective medium approximation to model the optical properties of crystallized a‐Si:H obtained by MIC

“…1 Introduction To reduce long processing times and high annealing temperatures the solid phase crystallization (SPC) of amorphous silicon (a-Si) has been modified to employ metals as catalysts for crystallization [1]. Known as metal induced crystallization (MIC) of silicon, the process was successful on a-Si or hydrogenated amorphous silicon (a-Si:H) grown by various deposition techniques, using both eutectic and non-eutectic metals [2].…”