Variable range photodetector and method thereof

A photodetector for detecting photons in a predetermined wavelength range comprising:

• a substrate;
• a n-type layer located above the substrate suitable for forming a n-metal contact thereon;
• a first region in which the absorption and multiplication of carriers occurs, the first region having a crystalline structure having a growth direction and a first total polarization having a magnitude and direction;
• a second region adjacent to the first region, the second region having a crystalline structure having a growth direction and a second total polarization having a magnitude and direction, the first and second regions forming a first interface therebetween, the magnitudes and directions of the first and second total polarizations being such that a scalar projection of second total polarization on the growth direction is greater than a scalar projection of the first total polarization projected onto the growth direction thereby creating a negative first interface charge;
• and
• a third region suitable for forming a p-metal contact thereon, the third region having a crystalline structure having a growth direction and a third total polarization having a magnitude and direction, the second and third regions forming a second interface therebetween, the third total polarization having a scalar projection on the growth direction that is less than the scalar projection of the second polarization onto the growth direction, creating a positive second interface charge;
• the first and second interface charges separated by the thickness of the second region creating an electrostatic potential barrier to carriers of differing energy levels;
• the electrostatic potential barrier defining a predetermined wavelength range of the photodetector.

A method of making a photodetector which detects light in a predetermined spectrum comprising;

• providing a substrate;
• forming a p-type contact region on the base;
• forming a first region in which the absorption and multiplication of carriers occurs, the first region having a first total polarization;
• a first region in which the absorption and multiplication of carriers occurs, the first region having a first total polarization;
• forming a first interface by forming a second region adjacent to the first region, the second region having a magnitude of the second total polarization greater than the magnitude of the first total polarization of the first region;
• forming a second interface by forming a third region comprising an n-metal contact region, the third region having a magnitude of the third total polarization that is less than the magnitude of the polarization of the second region, the polarizations of the first and second regions operating to create a first interface charge at the first interface and the polarizations of the second and third regions operating to form a second interface charge at the second interface;
• the first and second interface charges creating an electrostatic potential barrier to carriers of differing energy levels;
• adjusting the electrostatic potential barrier by adjusting the one of the thickness of the second region, the voltage differential across the photodetector, or the material composition or doping of the first, second or third regions to define a predetermined wavelength range of the photodetector.