1N4148 replacement

Hi,

In an oscillator which uses two 1N4148 diodes as switching diodes to turn the gate of the two FETs on/off at the frequency of 100Khz, I have increased the supply voltage by factor 2, the circuit works good now as well but the 1N4148 diodes get warm, I want to replace them by a Just similar but higher power diodes, What is your suggestion for the alternative?

I used two UM4007 instead of 1N4148's but the output was reduced somewhat, I thought maybe thats due to 0.7 of voltage reduction for these diodes, so...?!

Define warm? Semiconductors will run perfectly fine at temperatures that can cause physical pain if not outright burns to a human being. Have you determined how much power the diode's are actually using? You can't chose a new diode without knowing your power requirements. 100khz is not very fast, virtually any generic switching diode will work, a schottky diode may be a good choice because of the low voltage drop power loss will be lower so dissipation will be less, again though without knowing the voltage you're using and the power being dissipated by your current diodes we can do nothing but guess.