A 4 5 6

Surface Science 174 (1986) 509-513 North-Holland, Amsterdam

T R A N S P O R T I N V O L V I N G S U P E R L A T Y I C E M I N I B A N D S

R . A . D A V I E S , M. J . K E L L Y a n d T . M . K E R R

GEC Research Limited, East Lane, Wembley, Middlesex, England

Received 27 July 1985; accepted for publication 10 September 1985

509

We report the observation of negative differential resistance intrinsic to the miniband structure of a semiconductor superlattice. The time and magnetic field dependences of the I - V characteris- tics are described.

514 Surface Science 174 (1986) 514-518 North-Holland, Amsterdam

G E N E R A L I Z E D T H E O R Y O F I M P A C T I O N I Z A T I O N I N

M U L T I L A Y E R E D S E M I C O N D U C T O R S T R U C T U R E S

K c v i n B R E N N A N

School of Electrical Engineerin~ Georgia Institute of Technology, Atlanta, Georgia 30332, USA Received 29 July 1985; accepted for publication 12 September 1985

We present a general theory of impact ionization in superlattice avalanche photodiode (APD) devices particularly for those structures in which the carriers obtain no net energy gain from the superlattice itself, the quantum well and undoped channeling APD. It is found that two mecha- nisms operate to enhance the electron ionization rate. The sudden large increase in kinetic energy derived from crossing a heterobarrier increases the probability of semiballistic impact ionization. Simultaneously, the carriers are heated by the field while within the A1GaAs layer, such that upon re-entry into the GaAs layer the distribution is hotter than before. Carrier heating by the field is particularly important when the field is applied parallel to the layers as in the undoped channeling APD.

Surface Science 174 (1986) 519-521 North-Holland, Amsterdam

P R O P O S A L O F N O V E L T R I O D E D E V I C E

U S I N G M E T A L - I N S U L A T O R S U P E R L A T T I C E

F O R E X T R E M E L Y H I G H S P E E D R E S P O N S E

Y a s u y u k i N A K A T A , M a s a h i r o A S A D A a n d Y a s u h a r u S U E M A T S U

Department of Physical Electronics, Tokyo Institute of Technology, 2-12-10-okayama, Meguro-ku, Tokyo 152, Japan Received 1 October 1985; accepted for publication 25 March 1986

519