This paper describes the growth of both InAsP single layers and InAsP/InGaAsP multi-quantum-well (MQW) structures by metalorganic molecular beam epitaxy (MOMBE). The As/P ratio in the InAsyP1-y films is proportional to the ratio of the AsH3/PH3 supply sources. The well-number dependence of the MQWs is characterized by X-ray analysis, photoluminescence (PL), and transmission electron microscopy, revealing that the critical thickness of InAs0.5P0.5 is approximately 70 nm at 520 degrees C. The PL spectrum of an MQW with 8 nm thick InAsP well layers has a full width at half maximum (FWHM) of 4.1 meV at 4 K. The MQW lasers have a threshold current density of 0.74 kA/cm(2) with a cavity length of 300 mu m. The maximum operating temperature is as high as 145 degrees C for a 10-well MQW laser with cleaved facets.