Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
Giving money instead of slaughtering an animal in Aqiqah is not sufficient. Aqiqah is a symbol of Islam and a confirmed Sunnah so actually slaughtering an animal is recommended in Shariah. Hence, one should not make giving money as a replacement of Aqiqah.
The Imams of Sunan narrated from Samurah who narrated from the Prophet (Sallallahu Alaihi wa Sallam) that he said: "Every new born is mortgaged to his Agiqah, it should be slaughtered on behalf of him, on his seventh day. He should be given a name on that same day and his head clean shaved."
Muslim jurists clearly state that slaughtering in Aqiqah is more appropriate than giving the price of the animal in charity, unless if there is a dire need of money for Muslims, or they need money to make Jihad against their enemies. In this given situations giving money is preferred considering the need of the Muslim Ummah.
As for other details of Aqiqah, please read the Fatwa: 83120.
Allah knows best.