We demonstrate the fabrication and electrical characterization of X-gate Tunnel Field Effect Transistors (TFET) based on p-Si/i-Si/n(+)Si(0.7)Ge(0.3) heterostructure nanowires grown by Chemical Vapor Deposition (CVD) using the vapor-liquid-solid (VLS) mechanism. The electrical performances of the p-Si/i-Si/n(+)Si(0.7)Ge(0.3) heterostructure TFET device are presented and compared to Si and Si0.7Ge0.3 homostructure nanowire TFETs. We observe an improvement of the electrical performances of TFET with p-Si/i-Si/n(+)Si(0.7)Ge(0.3) heterostructure nanowire (HT NW). The optimized devices present an Ion current of about 245 nA at V-DS = -0.5 V and V-GS = -3 V with a subthreshold swing around 135 mV/dec. Finally, we show that the electrical results are in good agreement with numerical simulation using Kane's Band-to-Band Tunneling model. (C) 2016 Elsevier Ltd. All rights reserved.