InGaP/InGaAlP double-heterostructure and multiquantum-well laser diodes grown by molecular-beam epitaxy

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Abstract
Room‐temperature continuous‐wave (cw) operation is achieved in the MBE (molecular‐beam epitaxy)‐grown InGaP/InGaAlP double‐heterostructure (DH) visible laser diodes with a threshold current of 110 mA. The lasing wavelength and threshold current density under pulsed operation are 666 nm and as low as 3.9 kA/cm2, respectively. This result is achieved by the introduction of H2 into the growth chamber during growth, the continuous growth from one layer to the next layer, and the introduction of a GaAs buffer layer. InGaP/InGaAlP quantum well structures are also grown. From photoluminescence measurements, the conduction‐band discontinuity ΔEc is estimated to be 0.43 of the band‐gap difference ΔEg. Furthermore, the multiquantum‐well (MQW) structure is found to be stable under thermal treatment at temperatures as high as 750 °C. Room‐temperature pulsed operation of InGaP/InGaAlP MQW laser diodes is achieved for the first time. The lasing wavelength is 658 nm with a threshold current density of 7.6 kA/cm2. cw operation is also achieved in the MQW laser diodes at −125 °C.