The alternate injection of trimethylindium (TMI) and tertiarybutylphosphine (TBP) without precracking was studied to expand the self-limiting growth conditions of an InP layer on InP substrates in ultrahigh vacuum, The range of growth conditions for self-limiting growth using TMI expanded two-fold compared to that using triethylindium (TEI). The carbon concentration in the InP layer grown using TMI was almost the same as that using TEI under self-limiting growth conditions. The growth rate of approximately 0.75 monolayers per cycle at the plateau was achieved on (0 0 1)-, (1 1 1)A-, and (1 1 1)B-oriented InP substrates. It was suggested that the decomposition process of TMI is identical to that of TEI and that the growth rate with the self-limiting growth conditions results from the surface occupancy of phosphorus precursors.