Formation of mid-infrared emissive InAs quantum dots on a graded In _xGa_1-xAs/InP matrix with a more uniform size and higher density under safer growth conditions

InAs mid-infrared emissive quantum dots (QDs) grown on a graded In _xGa_1-xAs/InP matrix with more uniform size and higher dot density have been successfully prepared by low pressure metal organic chemical vapour deposition (LP-MOCVD) under safer growth conditions. Low toxic tertiarybutylarsine and tertiarybutylphosphine sources were used to replace the high toxic arsine and phosphine in the MOCVD growth. To improve the process safety further, inertial N₂ instead of the normally used explosive H₂ was used as the carrier gas. Initially, by using a two-step growth method, uniform InAs QDs with a high dot density of 1.3 × 10 ¹⁰cm^-2 have been successfully grown on a InGaAs/InP matrix. The emission wavelength of the QDs reaches >2.1νm. The low temperature photoluminescence spectrum of the QDs grown by the two-step growth has much narrower linewidth and higher intensity than that of the QDs grown by using normal Stranski-Krastanow (S-K) and atomic layer epitaxy (ALE) growth methods.