Improvement in electrical performance of half-metallic Fe₃O₄/GaAs structures using pyrolyzed polymer film as buffer layer

Abstract

In this work, the Fe₃O₄ magnetic nanoparticles (MNPs) were synthesized by a colloidal method. TEM images reveal that Fe₃O₄ MNPs are spherical in shape with a narrow size distribution in the range of 6–7 nm. These MNPs were used in the fabrication of two types of n-GaAs-based structures: (i) Fe₃O₄/n-GaAs (reference); and (ii) Fe₃O₄/PPF/n-GaAs. We present that carbon-based pyrolyzed polymer films (PPFs), as a buffer layer, can control the electrical characteristics of a conventional Fe₃O₄/n-GaAs device. The behaviour of the apparent barrier height and ideality factor with the interfacial layer due to the presence of the interface state density is discussed. PPF raises the barrier height in a Fe₃O₄/PPF/n-GaAs half-metallic/insulator/semiconductor (h-MIS) device as high as 0.62 0.002 eV. Furthermore, Fe₃O₄/PPF interfaces exhibit unique electronic properties including high-quality interface, low series resistance (from 17.73 kΩ to 85.66 Ω) and extremely low interface state density (1.76 × 10¹² eV⁻¹ cm⁻²). Compared to the electrical performance for the Fe₃O₄/n-GaAs junction, that for the Fe₃O₄/PPF/n-GaAs junction was enhanced.

Keywords:

• half-metallic/insulator/semiconductor (h-MIS) structures
• Fe₃O₄ nanoparticles
• pyrolyzed polymer film
• I–V measurements