The preparation method of the N-type ultra-high-purity
germanium single crystal comprises the following steps: S1, carrying out
zone melting on ultra-high-purity
germanium by adopting a
zone melting method, and carrying out low-temperature Hall detection to select a qualified product A of which the
conduction type is P type and the net carrier concentration NA-ND is less than or equal to 1E10cm <-3 >; s2, adopting a normal
czochralski method to grow an ultra-pure
germanium crystal, carrying out a low-temperature Hall test, and selecting a region-melting
dopant Y of which the
conduction type is N type and the net carrier concentration NA-ND is in the range of E11-E13cm <-3 >; s3, secondary
zone melting is carried out, the zone melting product A in the step S1 and the zone melting
dopant Y in the step S2 are put into a
quartz boat together for multiple times of zone melting, a high-purity germanium polycrystalline rod is obtained, a low-temperature Hall test is carried out, and a part with the
conduction type being N type and the net carrier concentration being smaller than or equal to 2E10cm <-3 > is selected as a
crystal dopant W; and S4, preparing the N-type ultra-high-purity germanium
single crystal, putting the zone-melting product A in the step S1 and the
crystal doping agent W in the step S3 into a
crucible together, carrying out normal Czochralski
crystal growth, and carrying out low-temperature Hall test to obtain the N-type ultra-high-purity germanium
single crystal of which the NA-ND is less than or equal to 2E10cm <-3 >.