Carbon-doped InAlAs grown by LP-MOVPE lattice matched on InP is investigated at various growth temperatures. The liquid source tertiarybutylarsin instead of arsine is used to realize a high layer quality, at reduced growth temperature and a low V/III ratio, Carbon tetrabromide serves as carbon doping source providing a high doping level and a small diffusion. A p-type doping is achieved at it growth temperature of 540 degreesC and below. The p-type doping concentration is proportional to the adjusted carbon tetrabromide flow rate. A doping, concentration of electrically activated acceptors of Lip to p = 1 x 10(20) cm(-3) is achieved at a growth temperature of 520 degreesC.