Describe how tunneling takes place in reversed bias

When junction is reversed biased, p-region moves up with respect to the n-region as a result, filled energy levels on p- side become opposite empty energy levels on the n-side. At this stage electrons tunnel through narrow space charges region from the higher energy levels on p- side to the lower energy levels on the n- side. Despite the fact that junction is reverse biased significant current flows. With the increase in reverse  bias,  more  and  more  electrons  tunnel  from  p-side  to  n-side  and  a  larger current flow. Hence reverse characteristic of a tunnel diode is liner, just like that of a resistor.