RF Characterization of Diamond Schottky p-i-n Diodes for Receiver Protector Applications

• Published in: IEEE microwave and wireless components letters Vol. 30; no. 12; pp. 1141 - 1144
• Main Authors: Surdi, Harshad, Ahmad, Mohammad Faizan, Koeck, Franz, Nemanich, Robert J., Goodnick, Stephen, Thornton, Trevor J.
• Format: Journal Article
• Language: English
• Published: IEEE 01.12.2020
• Subjects: Diamond; P-i-n diodes; power semiconductor device; Power semiconductor devices; Radio frequency; receiver protectors (RPs); Schottky diodes; SPICE model extraction
• ISSN: 1531-1309; 1558-1764
• DOI: 10.1109/LMWC.2020.3031219

Diamond Schottky p-i-n diodes have been grown by plasma-enhanced chemical vapor deposition (PECVD) and incorporated as a shunt element within coplanar striplines for RF characterization. The p-i-n diodes have a thin, lightly doped n-type layer that is fully depleted by the top metal contact, and they operate as high-speed Schottky rectifiers. Measurements from dc to 25 GHz confirm that the diodes can be modeled by a voltage-dependent resistor in parallel with a fixed-value capacitor. In the OFF state with a dc bias of 0 V, the diode insertion loss is less than 0.3 dB at 1 GHz and increases to 14 dB when forward biased to 7.6 V. With a contact resistance, <inline-formula> <tex-math notation="LaTeX">R_{C} </tex-math></inline-formula>, of 0.25 <inline-formula> <tex-math notation="LaTeX">\text{m}\Omega \cdot </tex-math></inline-formula>cm 2 and an OFF capacitance, <inline-formula> <tex-math notation="LaTeX">C_{\mathrm{\scriptscriptstyle OFF}} </tex-math></inline-formula>, of 17.5 nF/cm 2 , the diodes have an RF figure of merit <inline-formula> <tex-math notation="LaTeX">F_{\mathrm {oc}} = </tex-math></inline-formula> (<inline-formula> <tex-math notation="LaTeX">2\pi R_{C}\,\,C_{\mathrm{\scriptscriptstyle OFF}})^{-1} </tex-math></inline-formula> of 36.5 GHz. The RF model suggests that reducing <inline-formula> <tex-math notation="LaTeX">R_{C} </tex-math></inline-formula> to less than <inline-formula> <tex-math notation="LaTeX">5\times 10^{-5} \Omega \cdot </tex-math></inline-formula>cm 2 will enable input power rejection exceeding 30 dB. Compared to conventional silicon or compound semiconductor based power limiters, the superior thermal conductivity of the diamond Schottky p-i-n diodes makes them ideally suitable for RF receiver protectors (RPs) that require high power handing capability.