The spelling of the phrase "are charge" is determined by its pronunciation in phonetic transcription, which is /ɑːrchɑːrdʒ/. The first syllable "are" is pronounced with an open back unrounded vowel, while the second syllable "charge" is pronounced with a voiced palato-alveolar sibilant followed by the sound of a soft "j" as in "June." This spelling might be confusing for non-native speakers or those unfamiliar with English phonetics, but it accurately represents the sounds in the word.
The phrase "are charge" is not a common or standard phrase. It appears to be a combination of the verb "are" and the noun "charge". However, it is unclear what specific meaning or context you are referring to. If you can provide additional information or clarify the usage, I will be happy to help you with any etymology related to that specific phrase.