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The authors analyzed radiative efficiency of InGaN laser diodes (LDs) emitting at 405 nm. Based on semiconductor rate equations, the radiative efficiency is unambiguously determined by the analysis of electroluminescence characteristics. The radiative efficiency exceeds 70% even far below threshold of ∼3 mA at a high temperature of 80 °C. This highly radiative characteristic is attributed to reduced contribution of nonradiative recombination in LDs with low-dislocation-density active material. It is also found that the radiative efficiency is almost independent of threshold current, indicating that nonradiative recombination is not a major factor which determines lasing threshold in 405 nm emitting InGaN LDs having low dislocation density. [ABSTRACT FROM AUTHOR]

We report stable temperature characteristics of threshold current and output power in InGaN blue laser diodes emitting around 450 nm. The threshold current is changed by <3 mA in operation temperature range from 20 to 80 °C, and even negative characteristic temperature is observed in a certain temperature range. This peculiar temperature characteristic is attributed to originate from unique carrier transport properties of InGaN quantum wells with high In composition, which is deduced from the simulation of carrier density and optical gain. In addition, slope efficiency is also maintained well and wall plug efficiency is even improved as temperature increases. [ABSTRACT FROM AUTHOR]