The room temperature operation of visible vertical cavity surface emit
ting lasers at 642 nm is reported. A pulsed threshold current of 45 mA
for a 26 mu m diameter mesa device (corresponding to 8.5 kA cm(-2)) w
as achieved at an operating voltage of 3.5 V. Photoluminescence at 10
K showed that an In0.48Al0.3Ga0.22P direct barrier provides better ele
ctron confinement than an In0.48Al0.52P indirect barrier with unstrain
ed In0.48Ga0.52P quantum wells.