Growth of self-assembled InP quantum islands for red-light-emitting injection lasers

In order to achieve laser emission in the visible part of the spectrum, we have investigated the growth of self-assembled InP quantum dots on GaInP by low-pressure metal-organic vapor phase epitaxy (MOVPE) using the Stranski- Krastanow growth mode. Unlike the well-established InAs-GaAs system, when I nP is deposited on GaInP, typically, two types of coherently strained islan ds with different sizes are formed. A high density of small islands is favo red when using growth conditions with a reduced surface diffusion, i.e., Lo w temperatures, high growth rates, and substrates with high misorientation angles, After the deposition of 3.4 monolayers of InP at 580 degrees C on G aAs-substrates with a surface angle of 15 degrees to the next (111)B-plane, 2 . 10(10) InP dots per square centimeter with an average height of 4 nm w ere assembled. The emission of these InP islands at 1.72 eV (4.2 K) shows a n inhomogeneous broadening of 42 meV because of the size fluctuation of the quantum dots. At 90 K, lasing from self-assembled Inf quantum islands was observed above a threshold current density of 288 A/cm(2). The detected laser line is loca ted at 1.8 eV, about 80 meV higher than is the ground-state transition ener gy. We attribute this behavior to lasing from excited states in agreement w ith power-dependent photoluminescence experiments. For temperatures above 1 50 K, the threshold current density increases dramatically because of a the rmally activated escape of carriers up to 4.9 k17/cm(2) at room temperature , where the characteristic temperature is 35 K. Injection lasers containing stacked InP quantum islands and AlGaInP barrier layers with a higher band offset may exhibit an improved temperature dependence.