Novel SiGe/Ge heterojunction infrared detectors have, for the first time, been fabricated with Si1-xGex-Si heterostructures epitaxially grown on Ge substrates by rapid thermal process/very low pressure-chemical vapor deposition. The peak value of the spectrum response ranges from 1.3 to 1.55 mu m. The responsivity at 1.55 mu m is higher than 0.7 A/W at zero bias. The dark current density is as low as 4 x 10(-7) A/mm(2) at -5 V.