Avalanche photodiode multiplication region and avalanche photodiode with low impact ionization rate ratio

An avalanche photodiode comprising:

• a p-doped diode anode adapted for reverse-bias, electrically conductive engagement with the positive-charge-attracting cathode of an external energy source;
• an optical absorption region wherein photons energy is absorbed in the generation of electron-hole pairs;
• a charge-carrier multiplication region adapted to facilitate the generation, through impact ionization, of electron-hole pairs, each electron hole pair including an electron and a hole, wherein impact ionization by electrons is preferred over impact ionization by holes;
• and
• an n-doped diode cathode adapted for reverse-bias, electrically conductive engagement with the negative-charge-attracting anode of the external energy source,
• wherein the optical absorption region and the charge-carrier multiplication region are positioned between the diode anode and the diode cathode, with the optical absorption region being more proximate the diode anode than is the multiplication region, and the charge-carrier multiplication region comprises:
• at least one period of lattice structure comprising a first crystalline region having first and second sides and being fabricated from a first material having a first impact ionization threshold and a second crystalline region having first and second ends and joined, at the first end, to the second side of the first crystalline region at a first region-second region interface, the second crystalline region being fabricated from a second material having a second impact ionization threshold lower than the first impact ionization threshold, the first crystalline region including a first, p-doped layer and a second, n-doped layer separated by an intrinsic sub-region of the first crystalline region such that, when a reverse-bias voltage is applied across the avalanche photodiode, the first, p-doped layer assumes a negative charge, the second, n-doped layer assumes a positive charge and a localized electric field is present between the first and second charged layers, the first and second charged layers being arranged such that (i) each electron of a set of electrons having a travel path directed toward the second end of the second crystalline region, and extending through the first region-second region interface, encounters the first, negatively charged layer prior to encountering the second, positively charged layer, such that the electron is accelerated by the localized electric field prior to passing through the first region-second region interface and entering the second crystalline region where, due to the lower impact ionization threshold of the second crystalline material and the increased kinetic energy of the electron, the electron has a predetermined statistical probability of dissipating energy through impact ionization and generating additional electron-hole pairs at a predetermined statistical rate and such that (ii) each hole of a set of holes having a travel path directed toward the first side of the first crystalline region, and extending through the first region-second region interface, crosses the second region-first region interface prior to being accelerated by the electric field between the first and second charged layers but, due to the higher impact ionization threshold of the first material, has a lower statistical probability of dissipating energy through impact ionization within the first material at as high a statistical rate as does an electron in the second material.

An avalanche photodiode comprising:

• a p-doped diode anode adapted for reverse-bias, electrically conductive engagement with the positive-charge-attracting cathode of an external energy source;
• an optical absorption region wherein photons energy is absorbed in the generation of electron-hole pairs;
• a charge-carrier multiplication region adapted to facilitate the generation, through impact ionization, of electron-hole pairs, each electron hole pair including an electron and a hole, wherein impact ionization by holes is preferred over impact ionization by electrons;
• and
• an n-doped diode cathode adapted for reverse-bias, electrically conductive engagement with the negative-charge-attracting anode of the external energy source,
• wherein the optical absorption region and the charge-carrier multiplication region are positioned between the diode cathode and the diode anode, with the optical absorption region being more proximate the diode cathode than is the multiplication region, and the charge-carrier multiplication region comprises:
• at least one period of lattice structure comprising a first crystalline region having first and second sides and being fabricated from a first material having a first impact ionization threshold and a second crystalline region having first and second ends and joined, at the first end, to the second side of the first crystalline region at a first region-second region interface, the second crystalline region being fabricated from a second material having a second impact ionization threshold lower than the first impact ionization threshold, the first crystalline region including a first, n-doped layer and a second, p-doped layer separated by an intrinsic sub-region of the first crystalline region such that, when a reverse-bias voltage is applied across the avalanche photodiode, the first, n-doped layer assumes a positive charge, the second, p-doped layer assumes a negative charge and a localized electric field is present between the first and second charged layers, the first and second charged layers being arranged such that (i) each hole of a set of holes having a travel path directed toward the second end of the second crystalline region, and extending through the first region-second region interface, encounters the first, positively charged layer prior to encountering the second, negatively charged layer, such that the hole is accelerated by the localized electric field prior to passing through the first region-second region interface and entering the second crystalline region where, due to the lower impact ionization threshold of the second crystalline material and the increased kinetic energy of the hole, the hole has a predetermined statistical probability of dissipating energy through impact ionization and generating additional electron-hole pairs at a predetermined statistical rate and such that (ii) each electron of a set of electrons having a travel path directed toward the first side of the first crystalline region, and extending through the first region-second region interface, crosses the second region-first region interface prior to being accelerated by the electric field between the first and second charged layers but, due to the higher impact ionization threshold of the first material, has a lower statistical probability of dissipating energy through impact ionization within the first material at as high a statistical rate as does a hole in the second material.

An avalanche photodiode charge-carrier multiplication region adapted to facilitate the generation, through impact ionization, of electron-hole pairs, each electron-hole pair including an electron and a hole, and the movement of electrons in a first direction and of holes in a second direction anti-parallel to the first direction, wherein impact ionization by electrons is preferred over impact ionization by holes and the charge-carrier multiplication region comprises:

• at least one period of lattice structure comprising a first crystalline region having first and second sides and being fabricated from a first material having a first impact ionization threshold and a second crystalline region having first and second ends and joined, at the first end, to the second side of the first crystalline region through a transition, the second crystalline region being fabricated from a second material having a second impact ionization threshold lower than the first impact ionization threshold and the transition being fabricated from material exhibiting one of (i) a range of ionization thresholds lower than the first ionization threshold and greater than the second ionization threshold and (ii) a single ionization threshold lower than the first ionization threshold and greater than the second ionization threshold, the first crystalline region and the transition respectively including, at least in the presence of an externally applied electric field, a first, negatively charged layer and a second, positively charged layer separated by an intrinsic sub-region of the first crystalline region such that a localized electric field is present between the first and second charged layers, the first and second charged layers being arranged such that (a) each electron of a set of electrons having a travel path directed toward the second end of the second crystalline region, and extending through the transition, encounters the first, negatively charged layer prior to encountering the second, positively charged layer such that the electron is accelerated by the localized electric field prior to passing through the transition and into the second crystalline region where, due to the lower impact ionization thresholds of the transition and the second crystalline material, and the increased kinetic energy of the electron, the electron has a predetermined statistical probability of dissipating energy through impact ionization and generating additional electron-hole pairs at a predetermined statistical rate and such that (ii) each hole of a set of holes having a travel path directed toward the first side of the first crystalline region, and extending through the transition, enters the transition prior to being accelerated by the electric field between the first and second charged layers but, due to the higher impact ionization thresholds of the transition and first material, has a lower statistical probability of dissipating energy through impact ionization within the transition and the first material at as high a statistical rate as does an electron in the transition and the second material.

An avalanche photodiode charge-carrier multiplication region adapted to facilitate the generation, through impact ionization, of electron-hole pairs, each electron-hole pair including an electron and a hole, and the movement of electrons in a first direction and of holes in a second direction anti-parallel to the first direction, wherein impact ionization by holes is preferred over impact ionization by electrons and the charge-carrier multiplication region comprises:

• at least one period of lattice structure comprising a first crystalline region having first and second sides and being fabricated from a first material having a first impact ionization threshold and a second crystalline region having first and second ends and joined, at the first end, to the second side of the first crystalline region through a transition, the second crystalline region being fabricated from a second material having a second impact ionization threshold lower than the first impact ionization threshold and the transition being fabricated from material exhibiting one of (i) a range of ionization thresholds lower than the first ionization threshold and greater than the second ionization threshold and (ii) a single ionization threshold lower than the first ionization threshold and greater than the second ionization threshold, the first crystalline region and the transition respectively including, at least in the presence of an externally applied electric field, a first, positively charged layer and a second, negatively charged layer separated by an intrinsic sub-region of the first crystalline region such that a localized electric field is present between the first and second charged layers, the first and second charged layers being arranged such that (a) each hole of a set of holes having a travel path directed toward the second end of the second crystalline region, and extending through the transition, encounters the first, positively charged layer prior to encountering the second, negatively charged layer such that the hole is accelerated by the localized electric field prior to passing through the transition and into the second crystalline region where, due to the lower impact ionization thresholds of the transition and the second crystalline material, and the increased kinetic energy of the hole, the hole has a predetermined statistical probability of dissipating energy through impact ionization and generating additional electron-hole pairs at a predetermined statistical rate and such that (ii) each electron of a set of electrons having a travel path directed toward the first side of the first crystalline region, and extending through the transition, enters the transition prior to being accelerated by the electric field between the first and second charged layers but, due to the higher impact ionization thresholds of the transition and first material, has a lower statistical probability of dissipating energy through impact ionization within the transition and the first material at as high a statistical rate as does a hole in the transition and the second material.