Schottky Barrier Diodes Based on B-Doped Single Crystal Diamond Films – An Experimental and Theoretical Methodology

The growth of high quality heavily (p+) B-doped single crystal diamond (SCD) layers is prerequisite for the successful realisation of diamond-based high-power electronics. This presentation will zoom in on a combined experimental and theoretical approach of the impact of methane concentration on the deposition of heavily boron-doped (<i>p⁺</i>) single crystal diamond (SCD), in turn influencing the performance of Schottky barrier diodes based on said layers.<br/><br/>Using (100)-oriented high-pressure high-temperature substrates, optimized CVD growth conditions led to ~ 1.6 µm lightly B-doped (<i>p^–</i>) SCD films with an acceptor concentration of (1.0 ± 0.5) × 10¹⁶ cm^-3 on top of the <i>p⁺</i> layers [1]. To fabricate pseudo-vertical Schottky barrier diodes, Ohmic and Schottky contacts were sputtered on the <i>p⁺</i> and <i>p^– </i>layers, respectively.<br/><br/>It was already observed that the forward operation current of the diodes increased proportionally with increasing [CH₄]/[H₂] ratio (from 0.5 % to 3 %) used for the CVD of <i>p⁺</i> layer. This increase in current is associated with an increase in the doping level of the <i>p⁺</i> layers, a direct result of the increase of CH₄ concentration in the CVD plasma [1]. The Schottky barrier height and ideality factor of the diodes were determined and compared with theoretical calculations, where an ideal diode (n = 1) with a barrier height variation over the Schottky diode area agreed reasonably well with our experimental results. The diodes fabricated on samples with the <i>p⁺</i> layers grown at higher [CH₄]/[H₂] behaved similarly, except for their non-ideality (n &gt; 1) [2]. To conclude, the voltage-dependent ideality factor of the Schottky diodes will be discussed.<br/><br/><b>References</b><br/>[1] R. Rouzbahani, <i>et al.</i>, Carbon <b>172</b> (2021), 463-473.<br/>[1] R. Rouzbahani, K. Haenen, <i>et al.</i>, submitted (2023).