It is demonstrated that boron-doped nanowires have predominantly long-term stable wurtzite phase while the majority of phosphorus-doped ones present diamond phase. A simplified model based on the different solubility of boron and phosphorus in gold is proposed to explain their diverse effectiveness in retaining the wurtzite phase. The wurtzite nanowires present a direct transition at the Γ point at approximately 1.5 eV while the diamond ones have a predominant emission around 1.1 eV. The aforementioned results are intriguing for innovative solar cell devices.