First of thanking you very much for sharing this wonderful tool on PN junction. 

I am using MATLAB for solving the same kind of configuration of PN junction and got the same results as do in your simulator. 

But I have query related to to I V characteristic of the junction. You plotted current density vs voltage but what is the area of your device.

Could you please tell me the thickness of your device. ? 

Moreover its a one dimensional, is it correct to define current density instead of current ? 

kindly explain this please

Thanks