Asllani, Besar

Bevilacqua, Pascal

Hamad, Hassan

Locatelli, Marie-Laure

Phung, L,

Planson, Dominique

Raynaud, Christophe

Wei, L.

English

Archive Ouverte en Sciences de l'Information et de la Communication

HAL Id: hal-02138767
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Near breakdown voltage optical beam induced current
(OBIC) on 4H-SiC bipolar diode
Dominique Planson, Besar Asllani, Hassan Hamad, Marie-Laure Locatelli, L.
Wei, Christophe Raynaud, Pascal Bevilacqua, L Phung
To cite this version:
Dominique Planson, Besar Asllani, Hassan Hamad, Marie-Laure Locatelli, L. Wei, et al.. Near break-
down voltage optical beam induced current (OBIC) on 4H-SiC bipolar diode. International Conference
on Silicon Carbide and Related Materials 2017 (ICSCRM 2017), Sep 2017, Washington, United States.
pp.TH.DP.4. ￿hal-02138767￿
ID: 2757801 
	
Near breakdown voltage optical beam induced current (OBIC) on 4H-SiC 
bipolar diode 
 
D. Planson1), B. Asllani1), H. Hamad1), M.-L. Locatelli2) 3), L. Wei2) 3), C. Raynaud1), 
P. Bevilacqua1), L.V. Phung1) 
1) Université de Lyon, INSA Lyon, CNRS UMR 5005, Ampère, Lyon, France 
2) Université de Toulouse; UPS, INPT; LAPLACE (Laboratoire Plasma et Conversion 
d'Energie); 118 route de Narbonne, F-31062 Toulouse cedex 9, France 
3) CNRS; LAPLACE; F-31062 Toulouse, France 
dominique.planson@insa-lyon.fr 
 Silicon	Carbide	(SiC)	is	an	attractive	semiconductor	material	for	high	power	and	high	temperature	applications.	In	order	to	reach	the	expected	breakdown	voltage,	an	effective	junction	termination	is	required	 to	 spread	 the	 peripheral	 electrical	 field	 lines.	 Among	 different	 techniques	 used	 for	periphery	 protection,	 Junction	 Termination	 Extension	 (JTE)	 is	 often	 chosen.	 The	 key	 parameters	are	 the	 accurate	 dose	 of	 the	 electrically	 activated	 implanted	 dopants	 and	 the	 control	 of	 the	semiconductor	surface	charge	passivation.	SIMS	is	a	destructive	way	to	measure	the	concentration	profile	 of	 implanted	 species	 in	 the	 JTE	 but	 it	 does	 not	 allow	 to	 distinguish	 between	 electrically	active	dopants	and	 inactive	ones.	 In	 this	paper,	OBIC	 technique	 is	applied	 to	high	voltage	bipolar	diodes	 to	 observe	 the	 behavior	 of	 the	 periphery	 protection	 with	 respect	 to	 the	 applied	 reverse	voltage.	The	measured	OBIC	signal	(i.e	the	current	flowing	towards	the	reverse	biased	junction)	is	related	to	the	electric	field	in	the	bipolar	junction	space	charge.	For	 voltages	 near	 the	 breakdown	 voltage,	 the	 electric	 field	 becomes	 high;	 the	 electron-hole	paires	(EHPs)	which	are	generated	by	the	UV	beam	into	the	space	charge	region	are	accelerated	by	this	high	electric	field,	gained	enough	kinetic	energy	to	generate	new	EHPS	during	a	collision		with	the	atoms	of	the	crystalline	structure.	This	is	the	pre-avalanche	regim,	which	lead	to	an	increase	in	the	OBIC	signal	[1].	The	measurements	are	realized	on	a	square	bipolar	diode	protected	with	a	single	JTE.	The	anode	contact	 area	 radius	 curvature	 is	 set	 at	 200	 µm,	 and	 its	 total	 side	 length	 is	 700	 µm.	 The	 distance	between	 the	 metal	 periphery	 and	 the	 JTE	 extremity	 is	 250	 µm.	 A	 cross	 section	 of	 the	 device	 is	shown	in	Fig.	1.	The	surface	of	the	diode	is	scanned	by	the	laser	beam	focused	by	several	lens	in	a	spot	of	~10µm	diameter.	A	schematic	description	of	the	experimental	bench	is	shown	in	Fig.	2.	The	measurement	is	 performed	 in	 a	 vacuum	 chamber	 able	 to	 sustain	 high	 voltages	 up	 to	 3500V.	 Tests	 have	 been	carried	 out	 at	 0	 V,	 but	 also	 at	 higher	 voltages:	 1000	 V	 in	 Fig.	 3	 and	 2350	 V	 in	 Fig.	 4.	 Near	 the	breakdown	voltage,	an	increase	in	the	OBIC	signal	could	be	observed	at	the	edge	of	the	JTE	by	the	side	of	the	tip.	This	phenomenon	is	correlated	with	the	observed	luminescence	due	to	the	radiative	recombination	of	EHPs	generated	by	avalanche	multiplication	[2-3],	as	shown	in	Fig.	5.	More	 experimental	 results	 (including	 TCAD	 simulations)	 showing	 the	 variation	 of	 the	 OBIC	signals	 with	 the	 applied	 reverse	 voltages	 will	 be	 published	 in	 the	 final	 paper.	 Also	 theoretical	simulations	will	be	used	to	try	to	estimate	the	concentration	of	active	dopants.	
Acknowledgments:	 the	authors	would	like	to	thank	FilSiC	research	program	for	financial	support	and	also	gratefully	acknowledge	Dr.	Gregory	GROSSET	and	Lionel	DUPUY	for	the	realization	of	test	structures.	
1. H.	Hamad,	C.	Raynaud,	P.	Bevilacqua,	S.	Scharnholz,	D.	Planson,	Materials	Science	Forum	Vols.	821-823,	pp	223-228,	(2015).	2. S.	Ono,	M.	Arai,	C.	Kimura,	Jpn.	J.	Appl.	Phys.,	vol.	43,	n°.	10,	pp.	7107,-7108	(2004).			3. K.	Mochizuki,	H.	Okino,	H.	Matsushima,	Y.	Toyota,	Mater.	Sci.	Forum,	vols.	821-823,	pp.	640-643	(2015).	
	Fig.	1.	Cross	section	of	the	protected	bipolar	PiN	diode.	
	
	Fig.	2.	Schematic	of	OBIC	experimental	bench.	
	Fig.	3.	Top	view	of	OBIC	measurement	at	1000	V.	Position	of	the	tip	is	deduced	from	the	lower	signal	level.	
	Fig.	4.	2D-cartography	of	OBIC	signal	vs.	beam	position	at	2350	V	(current	is	expressed	in	nA).	
	Fig.	5:	Luminescence	observed	at	2351	V.	
x	(µm)	
y	(µm)	


Near breakdown voltage optical beam induced current (OBIC) on 4H-SiC bipolar diode

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Near breakdown voltage optical beam induced current (OBIC) on 4H-SiC bipolar diode

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