High quality InGaAsP/InGaAsP multiple quantum wells (MQWs) have been selectively grown by ultra-low-pressure (22 mbar) metal-organic chemical vapor deposition. A large bandgap energy shift of 46 nm and photoluminescence with FWHM less than 30 meV were obtained with a rather small mask width variation (15—30 μm). In order to study the uniformity of the MQWs grown in the selective area, novel tapered masks were employed, and the transition effect of the tapered region was also studied. The energy detuning of the tapered region was observed to be saturated at larger ratios of the mask width to the tapered region length.