Is it permissible to recite a Surah after Al-Fatiha in the emphasized Sunnah prayers (such as Fajr and Tahiyat Al-Masjid) using the Mus'haf or a mobile phone?

It is permissible to read from the Mus'haf (physical copy of the Quran) and from a mobile phone during both obligatory and supererogatory prayers, although it is better not to do so. The Sunnah regarding the recitation in the regular Fajr prayer is not to prolong it.