We compare strain-compensated quantum cascade lasers (QCLs) with two different waveguide designs and active regions with and without injector grown with solid source MBE. After installing a phosphorous source in our GEN 11 system and optimising the growth for thick InP layers, we were able to substitute our previous used GaInAs cladding layer with InP, yielding reduced losses and higher confinement factor. Fabricated devices using an InP waveguide layer revealed low threshold current densities (0. 15 kA/cm(2) at 77 K and 2.47 A/cm(2) at 300 K) and high-temperature operation up to 490 K in pulsed mode. Injector-free QCLs, called intersubband staircase lasers (SCLs) also benefit from an InP waveguide, leading to an increased maximum operation temperature up to 3 10 K and a relatively low threshold current density of 6.17 kA/cm(2) at 300 K. © 2005 Elsevier B.V. All rights reserved.