fast power diode using in buck switching regulator

[kamalifard]

hi
i am producing a buck regulator switching power supply in 200kHz the input is constant 375V DC and output sould have variable current output from 50mA to500mA the main diode is her307 T(on) of diode is very high for this aplication because of extra high reverse bias voltage and low bias current about 1 µsecond the that prohibit the control loop action.
what can i shorten this time can identify me a better diode that is accesible here if you know more than one tell me all (note that because of high frequency nominal current of diode should be higher than 1A ) or extra component that fasten diode
diode: http://www.secosgmbh.com:8081/datasheet/products/High_Efficiency/DO-27/HER301~HER307.pdf

 

[ronsimpson]

Input voltage 375V DC and you are using HER307 Diode with 70nS RRT.
I think you should use a HER 305 with a RRT of 50nS and a lower forward voltage drop.

DIODE SCHOTTKY 600V 3A IDH03SG60C
DELU1400-7, ES1G-13-F (25ns)
ES2G-13-F (35nS)
SF10GG-T, SF20GG-T, SF30GG-T (40nS)