Investigation of tensile‐strained InGaAlP multiquantum‐well active regions by photoluminescence measurements

The use of a tensile‐strained multiquantum‐well (MQW) active region in 630‐nm‐band InGaAlP MQW laser diodes is investigated through photoluminescence (PL) measurements. The critical conditions for lattice relaxation of strained MQW layers are also discussed. Emissions due to electron–heavy‐hole recombination and electron–light‐hole recombination are observed in the PL spectrum. A large energy difference (about 38 meV) is found between the two peaks, and radiative recombination is dominant in the MQW structure. These are thought to decrease the threshold current of tensile‐strained MQW laser diodes. The MQW active region is thought to be extremely close to the critical conditions for lattice relaxation, but no adverse effects on optical properties are observed. It is concluded that such a tensile‐strained MQW active region has advantages for use as the active region of 630‐nm‐band laser diodes.