InP/InGaAs double-heterostructure bipolar transistors (DHBTs), incorporating a new collector structure featuring ''pn pair doping'' in the heterointerface vicinity, have been fabricated using a low-pressure metalorganic chemical vapor deposition (MOCVD) method. These transistors provide high collector current densities over 1 X 10(5) A/cm2, indicating the successful suppression of current blocking. S-parameter measurements determine the high current gain cutoff frequencies of 130 GHz. These values favorably compare with those of conventional InGaAs-collector HBTs fabricated for comparison, suggesting that the InP collectors have excellent electron transport properties.