A. Wali, R. Padhan, R. Divan, P. Darancet, N. Pradhan, A.V. Sumant
Argonne National Laboratory,
United States
Keywords: 2D materials, 3D diamond, PN junctions, heterostructures
Summary:
Diamond has historically been considered as a promising material for developing high voltage and extreme condition power electronic devices. The promise stems from its remarkable properties which include superior thermal conductivity and large electric field strength in addition to high carrier mobilities. However, despite having a well-established p-type doping scheme, diamond lacks a stable and reliable n-type doping method at room temperature which has impeded any promising advancements in diamond-based electronics. Since the donor energy levels are situated deep within the bandgap, any device operation can only happen at significantly higher temperatures where the deep donors are thermally activated. Here, we circumvent this bottleneck by integrating for the first time, atomically thin n-type two-dimensional (2D) monolayers of molybdenum disulfide (MoS2) acting as a pseudo delta-doped layer with boron doped p-type polycrystalline and single crystal diamond to demonstrate both lateral and vertical 2D/3D heterostructure based p-n junction diodes, respectively, which operate at room temperature. From the measured current-voltage (I-V) curves, our two-terminal devices show an ideality factor (η) value of 6, a rectification ratio (RR) of 10^6, a reverse saturation current (I_s ) of 1 μA, and a ON⁄OFF ratio of ~ 10^8. Moreover, our p-n heterojunction can seamlessly operate at temperatures as high as 573K, without any degradation in the device characteristics due to diamond’s high thermal conductivity, which allows it to serve as an excellent heat sink. We also provide a discussion on the origin of the current rectification which primarily stems from tunnelling assisted interlayer recombination of majority carriers from the metal/2D junction into bulk diamond on application of forward bias voltage. We believe our demonstration can provide a holistic platform for the development of highly reliable and efficient diamond-based electronics integrated with low-dimensional materials.