The effects of growth conditions choice and post-growth layer exposure to hydrides have been studied in InP/AlInAs self-organized nanostructures grown by low pressure MOVPE. Here we show how the size and density of low-dimensional structures can be manipulated and controlled by changing growth parameters. The final nanostructures shape is governed by influence of hydrides exposure. For example, the arsenization protocols of the original InP dot structures represent the crucial step to the transformation from dots to rings (and domes). We also demonstrate photoluminescence (observed for the first time) from capped structures (where arsenisation was performed), showing very narrow, separate lines (with power dependencies characteristic for single quantum dots) in an attractive and extraordinarily broad spectral region. This is very hard to achieve with traditional SK type dots, grown either on GaAs or InP.