Breakdown-avalanche photon sensors array , which is implemented in CMOS technology, wherein the breakdown-avalanche photon sensors array has single photon sensitivity, comprising: a semiconductor substrate ; and an epitaxial layer , which is located above the semiconductor substrate ; and a breakdown-avalanche photon sensor , which is located within the epitaxial layer , wherein the breakdown-avalanche photon sensor comprises: a guard ring ; a lower layer and an upper layer within epitaxial layer , which form a sensitive breakdown-avalanche pn-junction , wherein the guard ring is located within the epitaxial layer at the edges of the sensitive breakdown-avalanche pn-junction ; wherein the guard ring comprises less doping than the upper layer and the guard ring is configured for suppression of a breakdown-avalanche process at edges of the breakdown-avalanche photon sensor due to a weaker electric field at or near a guard ring area compared to an electric field within a central region of the sensitive breakdown-avalanche pn-junction ; and a quenching element , which is electrically connected to an area of the pn-junction of the breakdown-avalanche photon sensor , wherein the quenching element is configured for quenching the breakdown-avalanche photon sensor after detection of a photon. a semiconductor substrate ; and an epitaxial layer , which is located above the semiconductor substrate ; and a breakdown-avalanche photon sensor , which is located within the epitaxial layer , wherein the breakdown-avalanche photon sensor comprises: a guard ring ; a lower layer and an upper layer within epitaxial layer , which form a sensitive breakdown-avalanche pn-junction , wherein the guard ring is located within the epitaxial layer at the edges of the sensitive breakdown-avalanche pn-junction ; wherein the guard ring comprises less doping than the upper layer and the guard ring is configured for suppression of a breakdown-avalanche process at edges of the breakdown-avalanche photon sensor due to a weaker electric field at or near a guard ring area compared to an electric field within a central region of the sensitive breakdown-avalanche pn-junction ; and a quenching element , which is electrically connected to an area of the pn-junction of the breakdown-avalanche photon sensor , wherein the quenching element is configured for quenching the breakdown-avalanche photon sensor after detection of a photon. a guard ring ; a lower layer and an upper layer within epitaxial layer , which form a sensitive breakdown-avalanche pn-junction , wherein the guard ring is located within the epitaxial layer at the edges of the sensitive breakdown-avalanche pn-junction ; wherein the guard ring comprises less doping than the upper layer and the guard ring is configured for suppression of a breakdown-avalanche process at edges of the breakdown-avalanche photon sensor due to a weaker electric field at or near a guard ring area compared to an electric field within a central region of the sensitive breakdown-avalanche pn-junction ; and a quenching element , which is electrically connected to an area of the pn-junction of the breakdown-avalanche photon sensor , wherein the quenching element is configured for quenching the breakdown-avalanche photon sensor after detection of a photon. <EOS>