HOT ELECTRONS IN GERMANIUM AND OHM'S LAW 



1033 



one = 1.3 X W corresponding to B = 12.8. The deviation between theory 

 and experiment would be still worse at 77°K, for which temperature the 

 curve of Figure A2 fits the data well, as is shown in Figure 5. 



',03 ' - " -10' 



E IN VOLTS PER CENTIMETER 



Fig. A2— The theoretical curves and their limiting forms. Some of the data from Fig. 

 2 are repeated here and some additional data from the original publication (Ryder and 

 Shockley loc. cit.) are shown by crosses. A scale of values of x and of approximate "tem- 

 peratures" is also shown. The dashed curve for T = \9^°K is drawn for the case of the 

 simple theory with c = 5 X 10» cm/sec; the change at 77°K would be even more marked. 



Above range III, the Ax"^ term makes an appreciable contribution. 

 When Ax- becomes large compared to B, the approximation of taking the 

 acoustical modes to be fully excited becomes questionable. This effect may 

 be estimated by comparing kT and the energy in an acoustical transition. 

 The ratio is approximately 



Pre 

 kT 



mxVyC 



2c 



kT kT V 



520 ^ 2 -1.3 -10' 

 300 * 1.26-10^ 



(A7.51) 



X = x/3. 



