Save xml file without converting characters to entities

It may be a simple solution, but so far didn’t have chance to find an answer to my problem. I am pulling hair out of my head to get it done.

Basically I have created DOM document and added some elements.
In one of the text there are a chinese characters included in form of html code ie: さら
when I use text with above html codes to createTextNode and then save as a separate file using save() function the text is converted and saved with leading entity ie: さら
Question is how can I create text node to prevent converting ‘&’ into entity?

For any help thanks a lot