The thermal and electrical properties of the promising semiconductor MXene Hf2CO2

Abstract

With the growing interest in low dimensional materials, MXenes have also attracted considerable attention recently. In this work, the thermal and electrical properties of oxygen-functionalized M 2 CO 2 (M = Ti, Zr, Hf) MXenes are investigated using first-principles calculations. Hf 2 CO 2 is determined to exhibit a thermal conductivity better than MoS 2 and phosphorene. The room-temperature thermal conductivity along the armchair direction is determined to be 86.25~131.2 Wm−1 K−1 with a flake length of 5~100 μm. The room temperature thermal expansion coefficient of Hf 2 CO 2 is 6.094 × 10−6 K−1, which is lower than that of most metals. Moreover, Hf 2 CO 2 is determined to be a semiconductor with a band gap of 1.657 eV and to have high and anisotropic carrier mobility. At room temperature, the Hf 2 CO 2 hole mobility in the armchair direction (in the zigzag direction) is determined to be as high as 13.5 × 10 3 cm 2 V−1 s−1 (17.6 × 10 3 cm 2 V−1 s−1). Thus, broader utilization of Hf 2 CO 2, such as the material for nanoelectronics, is likely. The corresponding thermal and electrical properties of Ti 2 CO 2 and Zr 2 CO 2 are also provided. Notably, Ti 2 CO 2 presents relatively lower thermal conductivity but much higher carrier mobility than Hf 2 CO 2. According to the present results, the design and application of MXene based devices are expected to be promising.