A detector diode, in order to deliver the highest sensitivity and lowest distortion, must be properly impedance matched to its RF source. An easy way to find the answer is to build and use the diode Detector Bias Box. Id is the diode current in Amps. Is is the diode Saturation Current. Vd is the voltage applied to the diode in volts.
Rs is the fixed series parasitic resistance of the diode in ohms.
The lower the value of n, the higher will be the very weak signal sensitivity. This equation is accurate if the values of Is and n do not change as a function of diode current. This assumption is correct for the Schottky diodes I have checked. Germanium ones I have checked do not accurately follow the Schottky equation. At high currents, Is increases from its value at low currents.