High power high efficiency silicon carbide RF MESFETs are fabricated using a novel structure utilizing lateral epitaxy. The MESFET employs buried p-type depletion stoppers grown by lateral epitaxy with subsequent planarization. The depletion stopper is epitaxially overgrown by the channel layer. The depletion stopper suppresses short channel effects and increases the operation voltage and the RF signal gain at high voltage operation. High breakdown voltages of over 200 Volts are achieved for single-cell components, however large-area transistors are limited to around 150 Volts. Single-cell components measured on-wafer demonstrate an Ft of 10 GHz and high unilateral gain. Packaged 6-mm RF transistors in amplifier circuits feature a saturated power of 20 W and a P1dB of 15W with a linear gain of over 16 dB at Vdd of 60 V for 2.25 GHz operation. Maximum drain efficiency is 56% for class AB operation, 48% at 1 dB compression point and 72% for class C at 2.25 GHz.